Data in motion storage system and method

ABSTRACT

A data storage system is disclosed that includes a recirculating loop storing data in motion. The data may be carried by a signal via the loop including one or more satellites or other vessels that return, for example by reflection or regeneration, the signals through the loop. The loop may also include a waveguide, for example an optical fiber, or an optical cavity. Signal multiplexing may be used to increase the contained data. The signal may be amplified at each roundtrip and sometimes a portion of the signal may be regenerated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.15/465,356, filed on Mar. 21, 2017, which claims the benefit of priorityfrom U.S. Provisional Patent Application No. 62/311,814, filed on Mar.22, 2016, the entire contents of each of which are incorporated hereinby reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to the field of information storagetechnology and, in particular, to a system in which information may bestored as electromagnetic radiation in motion, for example, as lasers orother optical beams carrying data and transmitted or reflected betweenstructures or within structures, cavities and/or with/using differenttransmission media, including vacuum, crystals, nonlinear media, freespace, optical waveguides or optical fibers.

BACKGROUND OF THE DISCLOSURE

In an electromagnetic communication system, a maximum transmissiondistance of the signal, such as a beam of light, is dictated by the lossexperienced by the signal in free space or in the optical fiber or otherwaveguide, the spreading of the signal carrying the data due to variousdispersive and nonlinear effects, and the addition of noise from sourcesincluding, but not limited to, perturbations of the system, randomscattering events and spontaneous emission of light. As a result, whentransmitting a signal over longer distances, the signal typically has tobe regenerated at various distance intervals. Full data signalregeneration is typically considered a “3R” process that includes dataretiming, reshaping, and reamplification (or amplification).

Laser-based data communication in space is well known. For example, theArtemis satellite of the European Space Agency has provided an opticaldata transmission link with the CNES Earth observation satellite, SPOT4. Communication range in space for optical communication is reliable atseveral thousand kilometers. Laser or optical communication overdistances orders of magnitude greater than this may also be achievable.NASA's Optical Payload for Lasercomm Science (OPALS) project has alsosuccessfully demonstrated high data transfer rates using opticalcommunication between Earth stations and the International SpaceStation. Another example, in January 2013, NASA transmitted lasersrepresenting an image of the Mona Lisa to a lunar reconnaissance orbiterroughly 390,000 kilometers away.

Conventional datacenters have a variety of drawbacks, including thatthey may be expensive to maintain, may require various types of media,and are subject to being hacked into and accessed physically or remotelywithout authorization, such that data may can be copied, destroyed, orotherwise changed without authorization access or attacked. In addition,power outages, natural disasters and calamities, such as fire, flooding,earthquakes, and war, can impact conventional terrestrial datacenters.Also data that has been erased from one of these data centers may berecoverable by a person with the right expertise. These data centersalso have the disadvantage of substantial overhead costs such as rent,cooling expenses, electricity costs, and physical security.Conventionally, data storage units can be built out of multiple racks,where each (data) rack is comprised of multiple hard drives in (whichcan be based on various technologies) and computers, such as routers,switches, firewalls, and other devices. This set up has numerouslimitations and challenges, including but not limited to, high operatingexpenses, as noted above, as well as requirements for rather largephysical locations, high consumption of electric power, significantmaintenance as well as high cooling needs.

Orienting and pointing of an electromagnetic beam in a laser context canbe done using a gimbal, or an optical phase array, as well as otherwell-known approaches used to point to a fine angular accuracy. Each ofthe signal transmitter may be selectively steered for opticalcommunication with the targets, such as reflecting surfaces. An inertialreference system may be used in concert with adjustable elevationsettings to track the neighboring satellites in the constellation. Beamsteering mirrors may be used to compensate for host satellite jitter andslight orbit differences. Further examples are provided in thediscussion in the National Academy of Science Study “Laser Radar:Progress and Opportunities in Active Electro-Optical Sensing” 2014chaired by Dr. Paul McManamon, attached herewith and incorporated infull herein by reference. Incorporated in full by reference herein arethe following: U.S. Pat. No. 5,602,838 to Kartalopoulos, U.S. Pat. No.6,002,916 to Lynch, U.S. Pat. No. 6,043,918 to Bozzay et al., U.S. Pat.No. 7,103,280 to Ionov et al., U.S. Pat. No. 8,913,894 to Coleman etal., U.S. 2010/0269143 to Rabowsky, U.S. 2010/0279604 to Wood, U.S. Pat.No. 4,856,862 to Passmore et al., U.S. Pat. No. 4,815,804 to Desurviewet al., U.S. Pat. No. 4,653,042 to d'Auria et al., U.S. Pat. No.5,862,286 to Imanishi et al., Pidishety, “Investigation of scalabilityof all-fiber fused mode selective coupler for generating multiple OAMstates,” in Proceedings of International Conference on Fiber Optics andPhotonics, 2016, U.S. Pat. No. 4,136,929 to Suzaki, McDonald et al.,“Spatial Solitary-Wave Optical Memory,” Journal of the Optical Societyof America B (Optical Physics), vol. 7, no. 7, pp. 1328-1335, 1990, Leoet al., “Temporal cavity solitons in one-dimensional Kerr media as bitsin an all-optical buffer,” Nature Photonics, vol. 4, pp. 471-476, 2010,U.S. Pat. No. 7,199,343 to Modley, U.S. Pat. No. 5,740,117 to Bona etal., Boyd et al., “Applications of Slow Light in Telecommunications,”Optics & Photonics News, vol. 17, no. 4, pp. 18-23, 2006, G.B.1998/000821 to Poustie et al., U.S. Pat. No. 4,479,701 to Newton et al.,U.S. Pat. No. 4,877,952 to Halemane et al., U.S. Pat. No. 4,469,397 toShaw et al., U.S. 2007/0081785 to Hays, U.S. Pat. No. 4,738,503 toDesurvire et al., U.S. Pat. No. 6,917,739 to Chen, U.S. Pat. No.6,172,926 to Drayer, U.S. Pat. No. 5,533,154 to Smith, U.S. Pat. No.5,566,261 to Hall et al., U.S. Pat. No. 6,647,163 to Song, U.S. Pat. No.5,058,060 to Su, U.S. 2003/0007230 to Kanko et al., U.S. 2002/0196488 toMyers, U.S. Pat. No. 4,166,212 to J. Judenstein, U.S. Pat. No. 4,473,270to Shaw, U.S. Pat. No. 8,582,972 to Small et al, U.S. 2009/0202191 toRamachandran, U.S. Pat. No. 7,177,510 to Ramachandran, U.S. Pat. No.7,110,651 to Golwich et al., U.S. Pat. No. 4,974,931 to Poole, and U.S.Pat. No. 7,103,239 to Kish, Jr. et al.

SUMMARY

A data storage system and method are described. In one embodiment, asystem according to an aspect of the disclosure includes a datamanagement system configured to manage digital data in the data storagesystem; a terrestrial transmitter configured to transmit a radiofrequency signal carrying the digital data to a communication satellite;the communication satellite configured to convert the radio frequencysignal to a signal and to transmit the signal to a first lasersatellite; the first laser satellite comprising a laser signal generatorconfigured to generate a laser signal carrying the digital data, and thelaser signal generator configured to transmit the digital data to asecond laser satellite; the second laser satellite configured to returnto the first laser satellite the digital data transmitted from the firstsatellite; and the first laser satellite configured to return to thesecond laser satellite the digital data transmitted from the secondlaser satellite, such that the digital data may be transmitted in arecirculating loop of storage in motion, wherein at least one of thefirst laser satellite and the second laser satellite may be configuredto retrieve a block of data of the digital data identified by the datamanagement system. A recirculating loop, according to an aspect of thedisclosure, may include a signal loop in which the signal is maintaineduntil the system is shut off or disassembled or until the signal iserased.

In such a system, the data management system may identify the block ofdata as being responsive to a request for the block of data received,the block of data being less than an entirety of the digital data.

According to another aspect of the disclosure, disclosed is a datastorage system that includes a recirculating loop configured to storedata in motion and comprising a first vessel and a second vesselpositioned remote from the first vessel; the first vessel comprising atleast one selected from the group consisting of a signal generator and asignal transmitter configured to transmit the data to the second vessel;the second vessel configured to return to the first vessel the datatransmitted from the first vessel; and the first vessel configured toreturn to the second vessel the data transmitted from the second vessel.A signal may be returned by reflecting all or part of it, or it may bereturned by regenerating the signal and transmitting it.

A data management system of such a data storage system may be configuredto manage the data in the data storage system, wherein at least one ofthe first vessel and the second vessel may be configured to retrieve ablock of data of the data identified by the data management system asbeing responsive to a data retrieval request for the block of datareceived from outside the data storage system, the block of data beingless than an entirety of the data.

In such a system, for each roundtrip of the signal through therecirculating loop the signal may be kept in motion.

In such a system, at least one of the first vessel and the second vesselmay be a satellite.

In such a system, at least one of the first vessel and the second vesselmay be a satellite in geosynchronous orbit around the earth. In such asystem, at least one of the first vessel and the second vessel may be aship, an aircraft, such as airplane, a hot air balloon, or a drone, asubmarine, or a stationary sea structure, for example, an oil rig.

In such a system, the recirculating loop may compare a third vessel, andthe second vessel may be configured to return the data to the firstvessel via the third vessel by transmitting the data to the thirdvessel.

In such a system, the recirculating loop may be configured torecirculate the data between vessels recurring in consecutive sequence.

In such a system, at least one of the first and the vessel may comprisea reflecting surface positioned and configured to return the signal.

In such a system, the second vessel may comprise a corner cubepositioned and configured to return the signal. A land station signallink to such a recirculating link may use electromagnetic signaling,such as RF or optical signals, or other type signaling.

In such a system, the at least one of the signal generator and thesignal transmitter may generate an electromagnetic radiation signalcarrying the data and transmitted to the second vessel.

In such a system, the at least one of the signal generator and thesignal transmitter may generate an optical beam signal, for example, alaser signal, carrying the data and transmitted to the second vessel.

In such a system, the at least one of the signal generator and thesignal transmitter may be configured to generate a multiplexedelectromagnetic signal comprising a first set of multiplexed signals,each signal of the first set of multiplexed electromagnetic signalscomprising a second set of multiplexed electromagnetic signals generatedusing a multiplexing scheme different from the first set of multiplexedsignals.

In such a system, the first vessel comprises a system asset tracker thatmay be configured to maintain position information regarding the secondvessel.

In such a system, the system may further comprise an error checkerconfigured to perform cyclic redundancy check to ensure data integrity.

Such a system may also include a controller configured to receive, at afirst time, a first request from outside the data storage system toperform a first operation, the first operation comprising one of a readoperation, a write operation, and a delete operation for a first blockof data of the data, and to receive, at a second time after the firsttime, a second request from outside the data storage system to perform asecond operation, the second operation comprising one of the readoperation, the write operation, and the delete operation for a secondblock of data of the data, wherein the system performs the firstoperation after performing the second operation.

In such a system, when the first operation is the read operation, thesecond operation may be the read operation; when the first operation isthe write operation, the second operation may be the write operation,and when the first operation is the delete operation, the secondoperation may be the delete operation.

In such a system, the at least one of the signal generator and thesignal transmitter may be configured to generate a code divisionmultiplexed signal as the signal, the code division multiplexed signalcomprising a first set of multiplexed signals such that a firstmultiplexed signal of the first set carries data other than a secondmultiplexed signal of the first set.

In such a system, the at least one of the signal generator and thesignal transmitter may be configured to generate an orbit angularmomentum division multiplexed signal as the signal, the orbit angularmomentum division multiplexed signal comprising a first set ofmultiplexed signals such that a first multiplexed signal of the firstset carries data other than a second multiplexed signal of the firstset.

In such a system, at least one of the signal generator and the signaltransmitter may be configured to generate a space division multiplexedsignal as the signal, the space division multiplexed signal comprising afirst set of multiplexed signals such that a first multiplexed signal ofthe first set carries data other than a second multiplexed signal of thefirst set.

In such a system, the at least one of the signal generator and thesignal transmitter may be configured to generate a polarization divisionmultiplexed signal as the signal, the polarization division multiplexedsignal comprising a first set of multiplexed signals such that a firstmultiplexed signal of the first set carries data other than a secondmultiplexed signal of the first set.

In such a system, the at least one of the signal generator and thesignal transmitter may be configured to generate a frequency divisionmultiplexed signal as the signal, the frequency division multiplexedsignal comprising a first set of multiplexed signals such that a firstmultiplexed signal of the first set carries data other than a secondmultiplexed signal of the first set.

Such a system may also include a data management system configured toassociate a data block carried by a portion of the signal with at leastone of a physical property and a location of the portion of the signal;and a controller configured to generate a control signal controlling anoperation on the data block, the control signal may be generated basedon a clock signal with reference to the at least one of the physicalproperty and the location of the portion of the signal.

Such a system may also include a data management system configured tomanage data in the data storage system and configured to receive arequest from outside the data storage system to at least one of delete,write and update a block of data in the data, wherein the recirculatingloop comprises an eraser configured to erase, based on informationreceived from the data management system, a first portion of the signal,the first portion carrying the data block, the data block being lessthan an entirely of the data.

According to another aspect of the disclosure, disclosed is a datastorage system including a recirculating loop configured to maintain alaser signal carrying the digital data in motion and including anoptical waveguide, an optical waveguide coupler, and a regenerator; asignal generator configured to generate a laser signal carrying thedigital data and to transmit the laser signal into an input/outputoptical waveguide; the optical waveguide coupler coupling the lasersignal between the input/output optical waveguide and the opticalwaveguide; and the regenerator coupled to the optical waveguide andconfigured to amplify and/or regenerate the laser signal through theoptical waveguide.

Such a system may also include a data management system configured tomanage digital data in the data storage system, wherein therecirculating loop may comprise an eraser configured to erase, accordingto timing based on information provided by the data management system, aportion of the laser signal carrying a block of data of the digitaldata, the portion of the laser signal being less than an entirety of thelaser signal.

In such a system, the signal generator may be configured to generate amultiplexed signal as the laser signal, the multiplexed signalcomprising a first set of multiplexed laser signals, such that a firstmultiplexed laser signal of the first set carries data other than asecond multiplexed laser signal of the first set, each laser signal ofthe first set of multiplexed signals comprising a second set ofmultiplexed laser signals generated using a multiplexing schemedifferent from the multiplexing scheme used to generate the first set ofmultiplexed signals.

In such a system, each laser signal of the second set of multiplexedlaser signals may comprise a third set of multiplexed laser signalsgenerated using a multiplexing scheme different from the multiplexingscheme used to generate the first set of multiplexed signals and fromthe multiplexing scheme used to generate the second set of multiplexedsignals.

According to a further aspect of the disclosure, a data storage systemdisclosed that includes a recirculating loop configured to maintain asignal carrying data in motion and including a waveguide and a waveguidecoupler; the waveguide coupler configured to couple a signal carryingthe data into the waveguide; and a signal conditioner configured tocondition the signal conveyed through the waveguide by at least one ofamplifying and regenerating the signal.

In such a system, the waveguide may comprise optical fiber.

Such a system may include a signal generator configured to transmit thesignal to the waveguide coupler, wherein the signal generated by thesignal generator may be an electromagnetic signal.

Such a system may include a signal generator configured to transmit thesignal to the waveguide coupler, wherein the signal generated by thesignal generator may be a laser signal.

In such a system, the recirculating loop may further comprise the signalconditioner, and the waveguide may comprise a first segment positionedto convey the signal between the waveguide coupler and the signalconditioner and a second segment connected to the signal conditioner,the first segment being free of direct physical connection with thesecond segment.

In such a system, the recirculating loop may comprise the signalconditioner, and the signal conditioner may comprise a signal amplifierconfigured to amplify at least a portion of the signal each time thesignal passes through the signal conditioner.

Such a system may include a data management system configured to managedata in the data storage system and configured to receive a request fromoutside the data storage system to at least one of delete, write andupdate a block of data in the data, wherein the recirculating loop maycomprise an eraser configured to erase, based on information receivedfrom the data management system, a first portion of the signal, thefirst portion carrying the data block, the data block being less than anentirely of the data.

In such a system, the data management system may be configured togenerate timing information according to the request, and theinformation received by the eraser from the data management system inthe timing information.

Such a system may include a signal generator configured to transmit thesignal to the waveguide coupler, wherein the signal carrying the datagenerated by the signal generator may be a signal multiplexed by apropagation-direction multiplexer configured to transmit a first portionof the signal through the recirculating loop in a first direction and totransmit a second portion of the signal through the recirculating loopin a second direction different from the first direction.

Such a system may include a signal regenerator, wherein the signalconditioner may be a signal amplifier configured to amplify at leastsome of the signal, wherein, the signal regenerator may be configured toregenerate, at a first timing, only a first portion of the signal, thefirst portion of the signal being less than an entirety of the signal,and to regenerate, at a second timing after the first timing, only asecond portion of the signal, the second portion of the signal beingless than an entirety of the signal.

In such a system, the system may regenerate the signal asynchronouslysuch that the second portion is a least recently regenerated portion ofthe signal.

In such a system, the system may regenerate only the first portion ofthe signal at a third timing, and may regenerate only the second portionof the signal at a fourth timing, an interval between the first andthird timing being greater than an interval between the second andfourth timing.

In such a system, the system may regenerate only the first portion ofthe signal interleaved with the regenerating of only the second portionof the signal.

Such a system may also include a controller configured to receive, at afirst time, a first request from outside the data storage system toperform a first operation, the first operation comprising one of a readoperation, a write operation, and a delete operation for a first blockof data of the data, and to receive, at a second time after the firsttime, a second request from outside the data storage system to perform asecond operation, the second operation comprising one of the readoperation, the write operation, and the delete operation for a secondblock of data of the data, wherein the system performs the firstoperation after performing the second operation.

In such a system, when the first operation is the read operation, thesecond operation may be the read operation; when the first operation isthe write operation, the second operation may be the write operation,and when the first operation is the delete operation, the secondoperation may be the delete operation.

Such a system may also include a data integrity determiner configured todetermine data integrity only of the first portion when the signalregenerator regenerates the first portion, and to determine dataintegrity only of the second portion when the signal regeneratorregenerates the second portion.

In such a system, the system may further comprise an error cyclicredundancy checker configured to perform cyclic redundancy check toensure data integrity.

In such a system, the recirculating loop may further comprise a signalfilter configured to impose signal loss on the signal in dependence, ina non-linear manner, on signal intensity of the signal.

In such a system, the recirculating loop may further comprise a signalfilter configured to filter out a portion of the signal with signalintensity below a first value.

In such a system, the recirculating loop further may comprise a signalfilter configured to provide signal loss to a first portion of thesignal, the first portion of the signal having a signal intensitygreater than a second portion of the signal, wherein the signal lossprovided may be mathematical function of a time varying intensity of thefirst portion of the signal.

In such a system, the recirculating loop may further comprise a signalfilter configured to provide signal loss to a first portion of thesignal and to a second portion of the signal, the first portion having asignal intensity greater than the second portion, wherein the signalloss provided to the first portion may be greater than a roundtrip gain,and the signal loss provided to the second portion may be less than theroundtrip gain.

In such a system, the recirculating loop further may comprise a signalfilter comprising a material with a first index of refraction, thesignal filter may be configured to provide a signal loss to a firstportion of the signal with a signal intensity below a first value, andto change the index of refraction of the material so as to provide asignal loss to a second portion of the signal with a second intensityhigher than the first value.

In such a system, the waveguide coupler may comprise a first coupler anda second coupler, the first coupler configured to couple only a firstportion of the signal, and the second coupler configured to couple onlya second portion of the signal other than the first portion, wherein thefirst and second portions are multiplexed in the signal as part of afirst multiplexing scheme.

In such a system, the first coupler may comprise a third coupler and afourth coupler, the third coupler configured to couple only a thirdportion of the signal other than the second portion, and the fourthcoupler configured to couple only a fourth portion of the signal otherthan the second portion and other than the third portion, wherein thefirst portion may comprise the third and fourth portions, and the thirdand fourth portions are multiplexed in the signal as part of a secondmultiplexing scheme different from the first multiplexing scheme.

In such a system, the waveguide coupler may comprise a signal in-couplerconfigured to transmit the signal into the waveguide, and a signalout-coupler configured to remove signal from the waveguide, wherein thesignal in-coupler may be positioned at the recirculating loop remotefrom the signal out-coupler.

In such a system, the waveguide may be a nanostructured optical fiber.

Such a system may also include a signal generator configured to transmitthe signal to the waveguide coupler, wherein the signal generator may beconfigured to generate a multiplexed electromagnetic signal as thesignal, the multiplexed electromagnetic signal comprising a first set ofmultiplexed electromagnetic signals, such that a first multiplexedsignal of the first set carries data other than a second multiplexedsignal of the first set, wherein each signal of the first set ofmultiplexed electromagnetic signals may comprise a second set ofmultiplexed electromagnetic signals generated using a multiplexingscheme different from the multiplexing scheme used to generate the firstset of multiplexed electromagnetic signals.

In such a system, each laser signal of the second set of multiplexedelectromagnetic signals may comprise a third set of multiplexedelectromagnetic signals generated using a multiplexing scheme differentfrom the multiplexing scheme used to generate the first set ofmultiplexed electromagnetic signals and from the multiplexing schemeused to generate the second set of multiplexed electromagnetic signals.

Such a system may also include a signal generator configured to transmitthe signal to the waveguide coupler, wherein the signal generator may beconfigured to generate a code division multiplexed signal as the signal,the code division multiplexed signal comprising a first set ofmultiplexed signals such that a first multiplexed signal of the firstset carries data other than a second multiplexed signal of the firstset.

Such a system may also include a signal generator configured to transmitthe signal to the waveguide coupler, wherein the signal generator may beconfigured to generate an orbit angular momentum division multiplexedsignal as the signal, the orbit angular momentum division multiplexedsignal comprising a first set of multiplexed signals such that a firstmultiplexed signal of the first set carries data other than a secondmultiplexed signal of the first set.

Such a system may also include a signal generator configured to transmitthe signal to the waveguide coupler, wherein the signal generator may beconfigured to generate a space division multiplexed signal as thesignal, the space division multiplexed signal comprising a first set ofmultiplexed signals such that a first multiplexed signal of the firstset carries data other than a second multiplexed signal of the firstset.

Such a system may also include a signal generator configured to transmitthe signal to the waveguide coupler, wherein the signal generator may beconfigured to generate a polarization division multiplexed signal as thesignal, the polarization division multiplexed signal comprising a firstset of multiplexed signals such that a first multiplexed signal of thefirst set carries data other than a second multiplexed signal of thefirst set.

Such a system may also include a signal generator configured to transmitthe signal to the waveguide coupler, wherein the signal generator may beconfigured to generate a frequency division multiplexed signal as thesignal, the frequency division multiplexed signal comprising a first setof multiplexed signals such that a first multiplexed signal of the firstset carries data other than a second multiplexed signal of the firstset.

Such a system may also include a data management system configured toassociate a data block carried by a portion of the signal with at leastone of a physical property and a location of the portion of the signal;and a controller configured to generate a control signal controlling anoperation on the data block, the control signal generated based on aclock signal with reference to the at least one of the physical propertyand the location of the portion of the signal.

Such a system may also include a data management system configured tomanage data in the data storage system and configured to receive arequest from outside the data storage system to at least one of delete,write and update a block of data in the data, wherein the recirculatingloop may comprise an eraser configured to erase, based on informationreceived from the data management system, a first portion of the signal,the first portion carrying the data block, the data block being lessthan an entirely of the data.

In such a system, the signal conditioner may be configured to provide afirst signal gain to a first portion of the signal, wherein the firstsignal gain may be provided according to information regarding signalintensity obtained for a previous roundtrip of the signal through therecirculating loop.

In such a system, the signal conditioner may be configured to providefiltering of the signal by providing signal amplification to a firstportion of the signal, wherein the signal amplification may be providedto the first portion when the first portion meets a phase-matchingcondition.

In such a system, the signal conditioner may be configured to provide apump beam and an idler beam, the pump beam and the idler beam configuredto provide the filtering.

Such a system may also include an optical cavity comprising arecirculating loop configured to maintain an optical signal carryingdata in motion, and the recirculating loop including a signal coupler, afirst signal returner, and a signal conditioner configured to conditionthe signal by at least one of amplifying and regenerating the signal;the signal coupler configured to couple at least a portion of the signalinto the optical cavity by transmitting the signal to the first signalreturner; the first signal returner positioned and configured to returnthe signal to the signal coupler; and the signal coupler configured toreturn the signal received from the first signal returner to the firstsignal returner.

In such a system, the signal coupler may comprise a signal in-couplerconfigured to transmit the signal into the optical cavity, and a signalout-coupler configured to remove signal from the optical cavity, whereinthe signal in-coupler may be positioned at the optical cavity remotefrom the signal out-coupler.

In such a system, the loop comprises a second signal returner, and thefirst signal returner may be configured to return the signal to thesignal coupler by transmitting the signal to the second signal returner.

In such a system, the optical cavity may comprise a continuousreflecting surface comprising the first signal returner and the secondsignal returner.

In such a system, the first signal returner may return the signal byreflecting the signal off a reflecting surface.

According to an aspect of the disclosure, also provided is a method offiltering an optical signal, the method including amplifying the opticalsignal by providing signal gain; and imposing signal loss on the opticalsignal in dependence, in a non-linear manner, on signal intensity of theoptical signal, wherein the imposing the signal loss includes providingsignal loss to a first portion of the optical signal, the first portionof the optical signal having a signal intensity greater than a secondportion of the optical signal, the signal loss provided to the firstportion being greater than the signal gain; and providing to the secondportion signal loss less than the signal gain.

In such a method, the signal loss provided may be a mathematicalfunction of a time varying intensity of the first portion of the signal.

In such a method, the signal filter may comprise a material with a firstindex of refraction, the signal filter configured to provide the signalloss to a third portion of the signal with a signal intensity below afirst value, and the method may comprise changing the index ofrefraction of the material so as to provide the signal loss to the firstportion of the signal with a second intensity higher than the firstvalue.

Also described is a data storage method using a recirculating loopconfigured to maintain a signal carrying data in motion and including asignal introducer and a signal returner. This method may includeintroducing, by the signal introducer, the signal carrying the data intothe recirculating loop; returning, by the signal returner, the signal tothe signal introducer; and returning, by the signal introducer, thesignal received from the signal returner to the signal returner.

In such a method, the signal returner may be a waveguide, and the signalintroducer may be a waveguide coupler configured to couple the signalbetween a signal generator and the waveguide.

In such a method, the signal returner may comprise a reflecting surface.

In such a method, the signal introducer may be positioned on a vessel.

Such a method may also include recirculating a first portion of thesignal through the recirculating loop in a first direction; andrecirculating a second portion of the signal through the recirculatingloop in a second direction different from the first direction, the firstportion being other than the first portion.

In such a method, a signal generator may be configured to generate amultiplexed electromagnetic signal as the signal, the multiplexedelectromagnetic signal comprising a first set of multiplexedelectromagnetic signals, such that a first multiplexed signal of thefirst set carries data other than a second multiplexed signal of thefirst set, wherein each signal of the first set of multiplexedelectromagnetic signals may comprise a second set of multiplexedelectromagnetic signals generated using a multiplexing scheme differentfrom the multiplexing scheme used to generate the first set ofmultiplexed electromagnetic signals.

In such a method, each signal of the second set of multiplexedelectromagnetic signals may comprise a third set of multiplexedelectromagnetic signals generated using a multiplexing scheme differentfrom the multiplexing scheme used to generate the first set ofmultiplexed electromagnetic signals and from the multiplexing schemeused to generate the second set of multiplexed electromagnetic signals.

In such a method, a signal generator may be configured to generate acode division multiplexed signal as the signal, the code divisionmultiplexed signal comprising a first set of multiplexed signals suchthat a first multiplexed signal of the first set carries data other thana second multiplexed signal of the first set.

In such a method, a signal generator may be configured to generate anorbit angular momentum division multiplexed signal as the signal, theorbit angular momentum division multiplexed signal comprising a firstset of multiplexed signals such that a first multiplexed signal of thefirst set carries data other than a second multiplexed signal of thefirst set.

In such a method, a signal generator may be configured to generate aspace division multiplexed signal as the signal, the space divisionmultiplexed signal comprising a first set of multiplexed signals suchthat a first multiplexed signal of the first set carries data other thana second multiplexed signal of the first set.

In such a method, a signal generator may be configured to generate apolarization division multiplexed signal as the signal, the polarizationdivision multiplexed signal comprising a first set of multiplexedsignals such that a first multiplexed signal of the first set carriesdata other than a second multiplexed signal of the first set.

In such a method, a signal generator may be configured to generate afrequency division multiplexed signal as the signal, the frequencydivision multiplexed signal comprising a first set of multiplexedsignals such that a first multiplexed signal of the first set carriesdata other than a second multiplexed signal of the first set.

In such a method, a data management system may be configured toassociate a data block carried by a portion of the signal with at leastone of a physical property and a location of the portion of the signal;and the method may further include generating a control signalcontrolling an operation on the data block, the control signal generatedbased on a clock signal with reference to the at least one of thephysical property and the location of the portion of the signal.

In such a method, a data management system may be configured to managedata in the data storage system; and the method may further includereceiving a request from outside the data storage system to at least oneof delete, write and update a block of data in the data; and erasing, byan eraser comprised in the recirculating loop, based on informationreceived from the data management system, a first portion of the signal,the first portion carrying the data block, the data block being lessthan an entirely of the data.

Such a method may also include providing, by a signal conditionerpositioned in the recirculating loop, a first signal gain to a firstportion of the signal, wherein the first signal gain may be providedaccording to information regarding signal intensity obtained for aprevious roundtrip of the signal through the recirculating loop.

Such a method may also include providing, by a signal conditioner,filtering of the signal by providing signal amplification to a firstportion of the signal, when the first portion meets a phase-matchingcondition.

Other features and advantages of the present invention will becomeapparent from the following description of the invention, which refersto the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates major constituents of a satellite-based informationstorage system, according to an example of the present disclosure.

FIG. 2A illustrates components of an Earth station that communicateswith the user and with the satellite-based information storage system,according to an example of the present disclosure.

FIG. 2B illustrates a system whereby the user communicates firstly witha satellite, where the Earth Station may or may not be used to hold allor part of the DMS and other components, according to an example of thepresent disclosure.

FIGS. 3-8 illustrate additional examples of positioning the satellites,according to an aspect of the present disclosure.

FIG. 9 is an illustration of an example of corner cube for receiving andreturning a signal.

FIGS. 10 and 11 illustrate examples of an electromagnetic signalsatellite transmitting an electromagnetic signal to a reflectionstructure, illustrated in FIG. 10 as a corner cube, and the satellitereceiving the reflected signal back, according to an aspect of thepresent disclosure.

FIG. 12 illustrates an example of communication system between a firstelectromagnetic signal communication device transmitting anelectromagnetic signal through a waveguide to a second electromagneticcommunication device, and the second electromagnetic communicationdevice transmitting the signal back to the first electromagneticcommunication device, according to an aspect of the present disclosure.

FIG. 13 is an illustration of an example of a terrestrial orsubterranean configuration in which a first electromagneticcommunication signal device transmits the electromagnetic communicationsignal to a reflector surface, which may be a corner cube or anothertype of reflector, which is then reflected back to the electromagneticsignal communication device, according to an aspect of the presentdisclosure.

FIG. 14 is an illustration of an example of an air-based implementationof an aspect of the invention, in which aircraft or other airbornevessels or vehicles or structures have electromagnetic signalcommunication devices which reflect, or regenerate and retransmit, theelectromagnetic signal to one another, according to an aspect of thepresent disclosure.

FIG. 15 is an illustration of an example of an air-based implementationin which one or more structure or an aircraft or airborne vehicle orvessel includes a first electromagnetic signal communication devicewhich transmits the electromagnetic signal to a second electromagneticcommunication device mounted on or to a second aircraft, illustrated forillustrative purposes as an airplane, which may be then reflected backto the first electromagnetic signal communication device, or has astructure such as a corner cube or other type of reflective surface thatreflects it back the electromagnetic signal to the first electromagneticsignal communication device, according to an aspect of the presentdisclosure.

FIG. 16 is an illustration of an example of another air-basedimplementation similar to the embodiment of FIG. 14, but theelectromagnetic signal communication devices and/or reflectivestructures are mounted on airborne vessels without jet engines orpropellers, shown, by way of example, as hot air balloons, heliumballoons or blimps, according to an aspect of the present disclosure.

FIG. 17 is an illustration of an example of a sea-based implementationof aspects of the invention in which a first electromagnetic signalcommunication device is mounted on a sea-based vessel or vehicle, shownby way of illustrative example as a submarine, transmitting theelectromagnetic signal to a second electromagnetic signal communicationdevice, which may be attached to or housed in a vessel, shown by way ofillustrative example as a ships and submarines, which then may reflectback the electromagnetic signal to the first electromagnetic signalcommunication device or may regenerate the signal and re-transmit theelectromagnetic signal to the first electromagnetic communicationdevice, according to an aspect of the present disclosure.

FIG. 18 is an illustration of an overview of a system for communicatingbetween signal receivers A and B using laser communication, with thereceivers forming a signal loop with a reflector, according to an aspectof the disclosure.

FIG. 19 is an illustration of an overview of a system for communicatingbetween signal receivers A and B using laser communication, with thereceivers forming a signal loop, according to an aspect of thedisclosure.

FIG. 20 is a schematic illustration of an example of a signal movingthrough a loop, such as through a waveguide.

FIG. 21 is a schematic illustration of an example of an electroniccontrol system to enable management of the data recirculating in aloop-based storage in motion system using a waveguide, according to anaspect of the present disclosure.

FIG. 22 is a schematic illustration of an example of a loop for datastorage in motion using a fiber optic spool, according to an aspect ofthe present disclosure.

FIG. 23 is a schematic illustration of an example of a system formodulating a signal, according to an aspect of the present disclosure.

FIG. 24A illustrates a spool of optical fiber used as a waveguide withconnecting transmitting and receiving hardware, which may be positionedin the same facility, container or remote from each other;

FIG. 24B illustrates a spool of optical fiber used as a waveguide withconnecting transmitting and receiving hardware, which may be positionedin the same facility, container or remote from each other, and a furthersuch configuration, which may be positioned in the same facility as thefirst configuration or may be positioned remote from the firstconfiguration;

FIG. 24C illustrates a spool of optical fiber used as a waveguide withfirst and second ends connected to the same electronic system forstoring information;

FIG. 25 is a schematic illustration of an example of a system forstorage in motion utilizing wavelength-divisionmultiplexing/demultiplexing of the signal within the recirculating loop,according to an aspect of the present disclosure.

FIG. 26 is a schematic illustration of an example of amplificationconditioning of the signal, according to an aspect of the presentdisclosure.

FIG. 27 is a schematic illustration of an example of a system forstorage in motion utilizing space division multiplexing system in anoptical waveguide loop, according to an aspect of the presentdisclosure.

FIG. 28 is a schematic illustration of an example of a system forstorage in motion utilizing propagation-direction division multiplexing(DDM) for the waveguide loop, according to an aspect of the presentdisclosure.

FIG. 29 is a schematic illustration of an example of a system utilizingwavelength division multiplexing, and/or space division multiplexing,and direction division multiplexing in a free space implementation of arecirculating loop, according to an aspect of the present disclosure.

FIG. 30 is a schematic illustration of an example of a passive nonlinearfilter for a loop providing stability to control signal gain and noisereduction, according to an aspect of the present disclosure.

FIG. 31A-F illustrate an example of how the nonlinear filter illustratedin FIG. 31 may provide gain stability and noise reduction for the signalrecirculating loop, according to an aspect of the present disclosure.

FIGS. 32A-C illustrate examples of recirculating loops, eachrecirculating loop formed by an optical cavity, according to an aspectof the present disclosure.

The Drawings illustrate examples of aspects of the disclosure. Otherfeatures and advantages of the disclosure will become apparent from thefollowing description of the invention, and/or from the combination ofone or more of the figures and the textual description herein, whichrefers to the accompanying drawings.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Disclosed are a method and system for storing information or any kind ofdata as electromagnetic radiation or as one or more other types ofsignals in motion. A recirculating loop maintains the signal carryingthe data in motion, for example. The recirculating loop may be formed ofsatellites or other vessels that reflect or otherwise retransmit thedata in free space or through a waveguide, such as one or more pieces ofoptical fiber. The recirculating loop may also include a coupler thatinjects signal into the recirculating loop and removes signal therefrom,a signal conditioner, such as an amplifier, that amplifies the signalrecirculating in the loop and may filter the signal. An optical cavitymay also be used to maintain the signal in a recirculating loop. Thenodes that reflect or otherwise return the signal may be repeated in aconsecutive order or the order of the nodes may vary from roundtrip toroundtrip. The waveguide implementation and the optical cavityimplementation may be provided as a terrestrial or other data center oras a stand-alone device and the signal may be a laser.

In one, example, a satellite-based laser, a land or on/under-water basedlaser or optical beam, or any as other electromagnetic radiation may beused to transmit and store data. Electromagnetic radiation orelectromagnetic beam as used herein may include any kind ofelectromagnetic signal, including a laser beam or signal, a maser beamor signal, an optical beam or signal, or any type of wired or wirelesssignal, including acoustic waves, radio waves, IR radiation, UVradiation, microwave-band transmission, or any combination of more thanone of the foregoing. While referred to herein sometimes simply as alaser beam or signal, other types of optical signals and other types ofelectromagnetic radiation transmissions, including radio waves,microwaves, IR, UV and combinations of bandwidths of wavelengths ofelectromagnetic radiation, whether guided, shaped, phased, or none ofthe foregoing, are also intended to be included. A satellite as usedherein can include a satellite or co-orbital objects, artificial ornatural, including but not limited to objects in LEO (low Earth orbit),MEO (medium Earth orbit usually understood as above LEO, approximately2,000 km, and below GEO, approximately 35,700 km-35,800 km), GEO(geostationary or geosynchronous orbit) or more distant orbits or in anyother orbits or positions including but not limited to orbiting theMoon, as well as other celestial objects, including but not limited toreflectors, mirrors, corner cubes, electromagnetic (RF, laser opticetc.) receivers and/or transmitters on the Moon, in Lagrangian(Lagrange) points, on space stations and/or in any other positions onearth, space, or in/on/under water. Further the term satellite as usedherein may refer to structures, such as reflective surfaces, including,for example, corner cubes, deployed alone as satellites or on, near, orin association with more conventional satellite structures. A signal, asused herein, may mean a beam, such as a laser or optical signal or aseries of signal bursts transmitted in succession. While sometimesreferred to herein as “information” or “data” it will be understood thatwhat is transmitted as part of the signal or beam may include any kindof data, including non-payload data, instructions, header and footerdata, encryption data, control data and other data. In some embodiments,data may be stored in motion as electromagnetic radiation within aspecific “hard drive” unit or storage device, data rack-mounted device,box computer system, fiber optics cable, free space or any other form orsubstance capable of transferring electromagnetic signals. According toone aspect of the disclosure, the loop may recirculate the signalwithout demodulating it and storing it as electrical signals. Forexample, the signal may be kept in continuous motion even if withreflections and/or amplifications and/or filtering. According to anotheraspect of the disclosure, the recirculating loop may include a temporaryelectronic data buffer through which some or the entire signal is madeto pass on each roundtrip or pass through the loop.

As illustrated in FIG. 1, Earth station 20 a transmits, for example, viaradio frequency transmission, commands for storing information in,updating and retrieving information from a satellite-based storagesystem. Earth station 20 a may communicate with communications satellite30 a, as shown in FIG. 1, by way of illustrative example. In anotherembodiment, the end user may communicate directly with the satellites ofthe data storage system using VSAT (very small aperture terminal) or anyother technology or any other form of electromagnetic communication. Theend user may use satellite or any other form of communication tocommunicate with the earth station 20 a, 20 b or directly with thesatellites 30, 40. A data management system, which may or may notinclude compression and/or encryption capabilities and which may be inthe Earth station 20 a, 20 b or on the satellites 30, 40 and/or in anyother location or part of any other component. Communication may be anRF communication or any type of electromagnetic communication or anycombination of multiple electromagnetic communication types. The Earthstation communications satellite 30 a may then relay this information toa group or constellation of satellites 40 a that implement the signalingfor storing the information. However, according to some embodiments,Earth station 20 a in some implementation communicates directly with thegroup of electromagnetic signal satellites 40 a.

The group of electromagnetic signal satellites 40 a passes to each otheroptical beams or other electromagnetic signals that carry data to encodeor store the data. While illustrated as a group of four, the group ofelectromagnetic signal satellites 40 a may include two or moresatellites, or one satellite and a reflector satellite (the reflectorpositioned on a satellite or elsewhere), or multiple reflector(s).According to some embodiments, one (or many satellites) and a reflectorpositioned on a Moon, Earth, or any other location may be used, or amoon, Earth or other celestial body, or atmosphere, surface or otherportion thereof, may be used as a reflector. The satellites 30, 40 maybe positioned in LEO, MEO, GEO, Lagrange points or in other orbits orpositions. The satellites 40 may have reflective surfaces that reflectthe signal back to the transmitting satellite, which then transmits itback to the same satellite, or may transmit it to a third satellite orto a fourth satellite, and so forth, creating a recirculating data loopback to the first satellite. Also, a first satellite of the group ofsatellites 40 a may transmit the signal to a second satellite of thegroup, which has one or more antennas or other receptors to receive thesignal and then regenerates the signal and transmits it back to thefirst satellite or to another satellite of the group, instead ofreflecting it. Signal may be thought of as being in continuous motion orin motion even if it may be reflected by a reflecting surface, such as acorner cube, or propagated through a waveguide as reflectance, asdescribed below. A signal may be returned by reflecting the signaland/or by some other way of turning around the signal, such astransmitting or retransmitting, or by a combination of amplifying andreflecting.

The satellite 40 may aim the beam at a corner cube, reflector, or anelectromagnetic communication receiver/transmitter (which could be onanother satellite, on Earth or on the moon or any other position), whichcan be a simple, relatively inexpensive device deployed in space. Inthis way, satellite 40 may be provided, the satellite transmitting datato one or more receiver satellites or corner cubes or other reflectors.A reflector, as used herein, includes not only devices that reflectradiation in the technical physical sense, such as a mirror, Braggreflector, or similar reflective surface, but also systems or devicesthe perform a substantially similar function of reversing or steeringpropagation of a beam, including but not limited to systems of two ormore mirrors or reflective surfaces, systems of one or more lenses,waveguides and fibers that steer propagation, and phase-conjugatemirrors that absorb radiation while simultaneously creating newradiation with identical or nearly identical properties andcharacteristics propagating in the reverse direction. A corner cube mayhave reflecting surfaces positioned and sized such that light hittingthe corner cube may be reflected back toward the source. Any suchreflecting device or system may be said to “reflect” the radiation inquestion without loss of the foregoing generality. For example, asatellite may transmit different signals to many receiver satellites orcorner cubes to achieve a large data (storage) capability byestablishing multiple loops or a transmission mesh network. Thesatellite 40 and the device (or other reflector) on the other endforming a second node may be positioned tens of thousands of kilometersapart. For example, a distance on the order of 10,000 km or 80,000 kmmay be used or any other distance.

A satellite 40 at the other end from a transmitting satellite mayreceive the data and then transmit the data back to the originatingsatellite. This can be performed many different ways, as would be knownto one of skill in the art. One example is to detect the light, convertinto electricity, and then retransmit back to the originating satelliteusing electronic circuitry and another set of lasers or other opticalsources. Another approach may be to recover the optical signals usingapertures and spatial mode converters, amplify the data signals using anoptical amplifier to compensate for transmission losses, and thenconvert the data signals back onto different spatial modes forretransmission back to the originating satellite. One can consider thisan optical re-transmitter, for example using a 1R amplification station,as discussed below.

Alternatively, the receiving node that reflects the beam from thetransmitting satellite may be, or may use, a corner cube (or otherreflector) positioned alone or near the receiving satellite. Thus whilesometimes described herein and illustrated in the drawings as asatellite that receives the beam the receiving node may be a reflectivesurface or other reflective device, such as, for example, a corner cube.Such reflective devices may also include transceivers that communicate aposition and/or orientation of the reflective device to a controllingsatellite, Earth Station or other node, and receive therefrominstructions for operation, including instructions to move position,change orientation, start operation, and the like.

The cross section of a corner cube may be sized such that light hittingthe corner cube is reflected back toward the source. A representation ofa corner cube is shown in FIG. 9. Light hits the corner cube, bouncesmultiple times, then returns toward the exact place from which the lightoriginated. The returned light may be a delta function in angle. Thebeam width of a beam limited by the diffraction limit is specified inequation (4) provided below. Lambertian scattering from a flat surfaceis reflected in a cosine pattern.

A corner cube can be a dihedral, which has two planes meeting andconcentrates light in only one dimension. Alternatively, a corner cubecan be a trihedral, concentrating light in two dimensions. A corner cubethat is a trihedral would have a cross section

$\begin{matrix}{\sigma \approx \frac{4a^{4}}{\lambda^{2}}} & (1)\end{matrix}$

where a is the diameter of the corner cube, and A is the wavelength ofthe light, assuming that the corner cube comprises a perfect mirror witha reflectivity of 1 which is a reasonable approximation of a typicalcorner cube. This compares to a reflected area with a surfacereflectivity which might be 3-20% of the illuminated area, or even more.The cross section of a flat surface is usually specified as:

σ=ρA  (2)

where ρ is the surface reflectivity and A is the illuminated area. Theequivalent antenna gain can be estimated by taking the ratio of thecross section in equation (1) to the cross section in equation (2).Corner cubes can be made using, for example, highly reflective surfacesso the surface reflectivity, p, can be approximated as 1 for a cornercube.

Upon return of the signal from the corner cube or other reflectivesurface, the originating satellite may regenerate the beam to the samecorner cube or to a different corner cube. Each satellite may have anumber of electromagnetic signal generators, or potentially, hundreds ofelectromagnetic signal generators, each generating a data beam.Generating a data beam may include generating an electromagnetic carrierwave, modulating the signal, amplifying the signal, multiplexing thesignal, transmitting the signal, or a combination of the foregoing.

The signal transmitted to Earth Station 20 a,b and from Earth Station 20a,b to the satellites may be encrypted to ensure security of data.Various encryption techniques may be used, including, for example,Advanced Encryption Standard (AES, sometimes known as Rijndael), or ahash function such as MD5 message-digest algorithm or the newer SHA-2(Secure Hash Algorithm 2). Various approaches to managing the data arecontemplated, including Apache Hadoop for distributed storage anddistributed processing. As illustrated in FIG. 2, Earth Station 20 maycommunicate with remote terrestrial nodes, for example, using a variouscommunication protocols such as TCP/IP and using any and allcommunication networks or means such as telephone system, including acellular network, or using any wireless or wired communication system orprotocol.

In order to maintain the same data over a long period, reamplificationof the signal carrying the data may be needed to re-amplify as needed ateach end of a communications loop. Over time, however, noise will buildup. A received signal may be amplified, while diverting a small portionof the amplified signal to use in determining whether errors havedeveloped.

An error detection and correction approach to replace corrupted data maybe used if desired for instance by error-correcting code which may bechecked periodically, to maintain uncorrupted data for long periods oftime. FIGS. 18 and 19 above show a basic concept.

Light may be transmitted from one laser, say laser A, to a receiver, B.If OAM modulation/muiltplexing is employed, we may need to demodulatethe light prior to amplification. Once the light is amplified a portionof the signal can be split off and examined for errors. Standard errordetection and correction schemes can be used. The corrupted data thenmay be replaced on either this round trip, or a subsequent round trip.

Each time an update to existing data is received, an instruction may betransmitted to a satellite, and the satellite (or satellites) may usethe signal receiver to search the electromagnetic signal beam for therelevant data file, for instance by monitoring the data that isautomatically received for the purpose of periodic 3R regeneration or atsome other point, or by some other means. Thus, each piece ofinformation may be assigned a file number, or another designator, whichmay be used as a header or footer, for example, before insertion in theelectromagnetic signal data stream. The electromagnetic signal datastream at time of conversion to electrical signal for regeneration ismonitored for the appropriate file number or some other designator orset of information that together provides a designation for each datablock. New data may also be added to the data stream at time ofelectromagnetic signal regeneration. Thus, Earth station 20 a,b mayassign a file number or some other designator to a range of data recordsassociated with a customer or user of the storage system. Upon receiptof a request to change or update information received from the user,Earth station 20 a,b may instruct that the data records associated withthat file number be rewritten to reflect the change or update. Forexample, Earth station 20 a,b may instruct the communications satellitegroup to transmit all the data records associated with the file number,which may be all the data records for the requesting user, to Earthstation 20 a,b, Earth station 20 a,b may make the change or update tothe data records of the file, and then transmit the changed or updatedfile to the communications satellite group. In the alterative, one ormore master satellites of the communications signal satellite group mayreceive the change or update request, together with the file number, andperform the change or update of the data records associated with thefile number.

Various types of electromagnetic signal generators and various types ofelectromagnetic radiation may be used to carry data. The same satellitemay have more than one type of electromagnetic signal generator, andmany types of modulation to encode at a high data rate are used. Forexample, a diode electromagnetic signal generator using a semiconductormay be used as part of a laser generator.

Electricity to power the electromagnetic signal generators and othercomponents of the system, as well as satellites 30, 40, may be obtainedfrom solar panels positioned on or near the satellite. However, othersources of power, including nuclear power, fuel or chemical power,battery power, capacitor-based charge, other sources of solar power, andthe like, or a combination of the foregoing, may be used in addition orinstead of solar power.

Each beam transmitted may include a number of different channels usingdifferent colors or wavelengths of the electromagnetic signal, which maybe distinguished by multiple methods including optical grating. This isknown as wavelength division multiplexing (“WDM”), or frequency divisionmultiplexing. For example, in some cases, as many as 160, or more,different such wavelength channels may be defined. For other types ofelectromagnetic radiation, the analogous frequency-division multiplexingmay be used, for example, for a radio carrier wave.

In addition, or in the alternative, different channels of data may becreated by use of electromagnetic signals of different polarizations,that is by “rotating” the light to different orientations. Other channelmultiplexing schemes include space division multiplexing, of which asubset is multiplexing of multiple beams each in an orthogonal, or nearorthogonal, spatial mode. An example of this is orbital angularmomentum. Note that spatial modes and polarizations can be combined toincrease the aggregate amount of data being transmitted. As mentionedabove, methods such as space (e.g., orbital angular momentum),polarization, and wavelength multiplexing as well as high order keyingsuch as QPSK or QAM may expand the amount of transmitted data, thusexpanding available storage when storing data in transmission.

As shown in the FIGS. 1, 3-8, a redundant Earth station 20 b, and aredundant Earth station communications satellite 30 b and a redundantgroup of electromagnetic signal satellites 40 b may also be provided.The redundant system can provide backup of all the data in case ofcatastrophic failure. Accordingly, the redundant system may store theidentical or nearly identical information or data as the group ofcommunications satellites 30 a. In the alternative, Earth station 20 b,Earth station communication satellite 30 b and second group ofelectromagnetic signal satellites 40 b may store different informationthan is stored by the group of electromagnetic signal satellites 40 a.In the alternative, or in addition, redundancy data “storage” can beachieved by having the same satellite or group of satellites transmitthe same beam to more than one receiving node and/or at more than onetime (similar to multicasting). That is, each satellite may transmit afirst electromagnetic signal embodying the information to a firsttarget, such as a second satellite or a reflecting structure or surface,and a second electromagnetic signal embodying the same information to asecond target, such as a second satellite or reflecting structure orsurface, to provide redundancy and disaster recovery for theinformation.

The aperture for electromagnetic signal generation could be set asneeded, depending on the distance between the transmitting satellite andthe reflector to which the beam is transmitted, the wavelength of thebeam, and other factors.

The size of the spot where the receiving terminal is located may becalculated as noted below.

The following discussion will explain aspects of the disclosure in thecontext of lasers, however other types of electromagnetic signals can beused as well. A laser beam will be emitted from one terminal or node andtravel to a second terminal or node. There are a number of differentconventions with respect to characterizing beam width. The followingequation may be used for the divergence angle, θ:

$\begin{matrix}{{\vartheta \approx \frac{\lambda}{D}},} & (3)\end{matrix}$

where λ is wavelength and D is the diameter of the transmittingaperture. For this approximate formulation of the diffraction limit, θmay be the full width at half maximum beam width. Laser communicationmay allow for long range communication because of the narrow beam. Forexample, comparing a 10 GHz frequency beam to a 200 THz frequency beam(1.5 micron wavelength), the beam width will be 20,000 times wider forthe RF beam. The variable d can be defined as the diameter of the beamspot at a given distance, R. In that case:

$\begin{matrix}{{d = {\frac{R\; \lambda}{D} + D}},} & (4)\end{matrix}$

The energy in a given photon is given by:

E _(p) =hv  (5)

where h is Plank's constant and v is frequency. The energy received by alasercom terminal is given by:

$\begin{matrix}{{E_{r} = {E_{t}*\frac{A_{r}}{A_{illum}}}},} & (6)\end{matrix}$

where A_(r) is the area of the receive aperture(s), and A_(illum) is thearea being illuminated. A transmit aperture of the same diameter as thereceive aperture would yield previous equations to obtain:

$\begin{matrix}{{N \approx \frac{E_{t}D^{4}}{{hc}\; \lambda \; R^{2}}},} & (7)\end{matrix}$

where N is the number of received photons. We can pick a number,depending on how sensitive the particular detector is. We can reversethis equation and obtain:

$\begin{matrix}{{D \approx \sqrt[4]{\frac{N\; h\; c\; \lambda \; R^{2}}{E_{t}}}},} & (8)\end{matrix}$

Turning to the issue of the required amount of power that a laser wouldput out, assuming transmission of B bits per second, which can be calleddata rate. Each bit will require E_(t) amount of energy. The laser poweris therefore the product of E_(t) and B. We can define

$\begin{matrix}{{E_{t} = \frac{P_{t}}{B}},} & (9)\end{matrix}$

This would yield

$\begin{matrix}{{D \approx \sqrt[4]{\frac{N\; h\; c\; \lambda \; B\; R^{2}}{P_{t}}}},} & (10)\end{matrix}$

Using this Equation 8 for laser aperture diameter for transmitting andreceiving, other values may be chosen to determine more or less optimaldiameters. Assuming a monostatic system, or at least the same aperturediameters for transmit and receive, we arrive at some values, providedby way of example, for Table 1. Table 1 is just an example for one baseassumption set, the aperture size and beam spreading will differ basedon multiple parameters, including but not limited, to the wavelengthsused, beam and aperture sizes, modes used, and distances transmitted.

TABLE 1 Lasercom Aperture Diameter Lasercom Aperture Diameter (cm)Wavelength Range B Pt D (microns) (Km) N (Gbps) (watts) (cm) 1.5 80000 110 10 3.7 1.5 80000 10 10 10 6.6 1.5 80000 100 10 10 11.7 1.5 80000 1040 10 93 1.5 80000 10 100 10 11.7 1.5 80000 10 1000 10 20.9 1.5 80000 1010000 100 20.9 1.5 80000 10 100000 500 24.8By way of further example, a 10,000 km distance may be used or someother distance, such as <10,000 km, 10,000-80,000 km, or >80,000 km.

For this set of assumptions, an aperture with a diameter ofapproximately 10 cm or with a diameter in the range of the above-namedvalues, may be used. However, apertures with smaller and largerdiameters are also contemplated. A laser on the order of 10 watt averagepower may be used for transmission in the context of some of the valuesprovided above, however, these values are provided merely by way ofillustration to show orders of magnitude for one particular example.This is a large trade space, so other assumptions are possible. Greaterand smaller diameter apertures and greater and smaller power lasers canbe used as well as different distances. Each beam or transmission may beas long as the distance between the transmitting satellite and thereceiving node, or may be shorter or longer than distance.

The user may wish to store or retrieve data by accessing the Earthstation 20 a,b. For example, the user may use an internet connection orother means to access Earth station 20 a,b or access the satellitesdirectly which will then communicate with the data management systemswhich could be in the earth station in or on the satellites or in anyother location or part of any other component. The Earth station 20 a,b,may have a number of components to route the communication to anappropriate group of users or organizations, provide security thatprotects against attacks and hacks, a buffer that temporarily stores theuser information that is being uploaded or being downloaded and the DataManagement System.

Earth station 20 a,b communicates with the satellites using anelectromagnetic signal transceiver, for example using RF signaling. Whenaccessing the Earth station, the user would be queried for credentialsby the DMS or the security system, including identification andpassword, or the like or otherwise verified. The DMS (Data ManagementSystem) may tag the data and its owner or the transmitting user forfuture access requirements, for retrieving information from thesatellite-borne “storage”, for billing purposes, for security reasonsand the like. Then, using the Earth station communication satellite, thedata is moved to the electromagnetic signal satellites for storage “inmotion” between the satellites. As discussed, according to an aspect ofthe present disclosure, the Earth station communication satellite may beomitted, such that Earth station 20 a,b may communicate directly withthe one or more electromagnetic signal satellites. Upon demand by theuser, the previously stored information is accessed using the Earthstation. The data management systems or any and all other components ofthe Earth Station could be in the earth station in or on the satellitesor in any other location or part of any other component.

Thus, according to an aspect of the disclosure, data may be “stored” bybeing kept in continuous motion, transmitted and reflected, with signalamplification also sometimes being necessary. According to an aspect ofthe disclosure, signal regeneration of a selected portion of the signalat each roundtrip or at each pass of a node may only be needed asnecessary due to the requirements of the electromagnetic beam carryingthe data. Where the distance between the satellites or othertransmitting nodes is equal, the beam capacity may be expressed as:

BC=(BBR*D*N)/C

BC=Beam Capacity (in bits),BBR=Beam Bit Rate (bps-bits per second)N=number of hops between the satellites (or nodes) in the beam pathD=distance between the satellites (or nodes) in the beam pathC=the speed of light (km/sec)If the distance between the satellites or nodes is not equal, then:

BC=(BBR*ΣD)/C

where the ΣD refers to the sum of all the distances in the beam path.For example, in an embodiment in which a satellite transmits the beam toa reflecting node, such as a corner cube, which reflects it back to thesatellite, which then has to receive and to regenerate the beam, ΣDwould be just twice the distance between the satellite and the cornercube, plus any distance traveled within the corner cube (which may benegligible for purposes of the above-noted equation).

For example, a public data network may be used. An authentication andapproval subsystem may be provided for verification and security. Therequested data is then obtained or retrieved from the group ofsatellites through the Earth station communications satellite 30 a,b tothe Earth station 20 a,b and passed back to the DMS facility and to thecustomer through a public data network. A local area network (LAN) orthe like may also be used to access the Earth station 20 a,b.

While sometimes described herein with reference to a satellite-basedembodiment, such an electromagnetic signal storage system may also bedeployed at sea, under water, in the air, on land, underground,utilizing, for example, existing fiber optic networks, new fiber opticnetworks, data racks, lighting up dark fibers, terrestrial or in outerspace, and on structures using a combination of the foregoing. Forexample, sea-based ships, vessels, or other mobile platforms orstationary structures, may transmit such electromagnetic signaling backand forth, as illustrated, for example in FIG. 17. As another example,land-based vehicles or stationary structures, fiber network(s), darkfibers, airborne electromagnetic signal system of network may transmitthe electromagnetic signals. Examples of aircraft-based implementationsare shown in FIGS. 14-16. Additional configurations of communicationsusing airborne vessels, such as aircraft, blimps, hot air balloons,communication towers, drones or a combination of the foregoing, whichmay also be transmitters, receivers and reflectors for theelectromagnetic signals, are illustrated in FIGS. 14-16. Or, acombination of the foregoing vessels, vehicles and structures may beused.

FIG. 29 is an example of a storage system 99 d using a free space loopusing wave division multiplexing (WDM), space division multiplexing(SDM), polarization division multiplexing (PDM), and direction divisionmultiplexing (DDM). A first vessel, such as a satellite 65, ispositioned in communication range with a second vessel 66. An opticalbeam 67, or some other type of electromagnetic radiation, may propagatethrough free space containing L×n×4 channels, each channel having aunique combination of spatial mode, polarization, propagation direction,and wavelength. Although discussed as propagating in free space, theelectromagnetic signal may be passed in whole or in part through anatmosphere, such as earth's atmosphere or the atmosphere of anotherplanet or through vacuum, or through space and/or through other media,such as water. The signal 67 is then returned from second vessel 66 tothe first vessel 65. Other components of the system that have beendescribed in the previous embodiments may also be included, such aslight source 1-i for producing light of wavelength j for a range ofwavelengths, the beam splitter 69-i, which splits each of the n signalsources into L*4 separate channels (for each spatial mode, polarization,and direction combination). For example, a fiber optic splitter orseveral fused fiber couplers may be used. Modulator 113-i, for exampleillustrated in FIG. 23, may be provided, and a radio frequency driver72-i may interface between control system 8 and components of themodulator 113-i using electrical connections 10. Input selector 73-i mayrecirculate the data in the channel or insert new data in the channelusing, for example, an optical switch or some other such element, andmay thus serve as an eraser 103.

Input selector 73-i may be implemented as an electro-optic switch drivenby control logic may be used, however all-optical switching may bepossible instead of all or some such switching. Input selector 73-iworks in concert with splitter 87-i to serve as an input/output coupler,similar to coupler 101 in FIG. 21. Collimator 74-i collimates lightemanating from optical fiber 90, which may be implemented using anaspheric lens on a translation stage. Converter 75-i coverts lightbetween spatial modes. In this way, each of the L beams emerging fromeach of the n light sources may be given a different spatial mode or aspatial mode and a polarization combination. This may be implementedusing two linear polarizers and a spatial light modulator (SLM), thatadd spatially varying phase to covert the light beam into a differentspatial mode.

Multiplexers 116 may provide free space multiplexing to coalign the axesof propagation of each of the 4Ln space beams, each beam having a uniquecombination of wavelength, spatial order, direction of propagation, andpolarization. This may be implanted, for example by log₂ (L×n×4)polarizing beam splitters and then, log₂ (√{square root over (L×n×4)})half-wave plates and log_(e) (L×n×4)² steering mirrors. Also, aninput/output separator 77 may be a beam splitter or a lower lossimplementation device. Optical isolators 78 separate the input andoutput channel in each propagation direction, and a Galilean telescope79 may be provided to control beam size by expanding it and collimatingthe beam and/or refocusing the beam. Beam steering 80 may be provided topoint the beam at the second vessel, and in particular, at thereflecting device or surface 81 on the second vessel. This may beaccomplished by, e.g., two steering mirrors, which may be optimizedusing piezoelectrically elements using control system 8 or a corner cubemay be provided. The reflector 81 may return the optical beam to firstvessel 65. A trihedral corner cube may be used, but a parabolic mirrorand/or by a pointer that points the beam at the first vessel 65 may beused instead.

Free-space demultiplexer 118A may be positioned to demultiplexed eachbeam into n beams, each beam of one distinct wavelength. This may beimplemented using a blazed grating or some other type of similar device.Further free-space demultiplexer 118B may be positioned to demultiplexeach of these 2*n beams in into 2*L beams with 1/2L times the originalpower. This may be implemented as log_(e) 2L polarizing beam splitters,log₂ √{square root over (2L)} half-wave plates, and log_(e) 2L² steeringmirrors. Converter 84-i may be positioned to convert a spatial modeselectively chosen and polarization combination to the fundamentalspatial mode (i.e. Gaussian beam). This may be implemented using ahalf-wave plate and an SLM, whose spatial pattern includes both theazimuthal variation exactly opposite the mode to be demodulated and aFresnel lens to condense the power of the correct spatial mode. Spatialmodes in addition to the mode in which azimuthal variation is exactlyopposite the pattern on this SLM may be difficult to focus down tightlyby the Fresnel lens because of the destructive interference at theircenters.

Coupler 85-i may be provided to couple a free space beam into opticalfiber 90. This may be accomplished using an aspherical lens on atranslation stage. In this way, the fiber may be used as a spatialfilter by efficiently coupling the spatial mode for this channel, whoseazimuthal pattern is exactly opposite to the pattern on the spatial modeconverter 84-i. The 1R regenerator 102-i is illustrated, by way ofexample in FIG. 26, however, in this free space implementation anyamplifier or combination of amplifiers that is compatible with the usedwavelengths, spatial mode, direction, and polarization multiplexing maybe used. Splitter 87-i splits the guided wave into substantiallyidentical signals. The output of this splitter 87-i may be transmittedto receiver or demodulation system 88-i, such as a photodiode orcoherent optical receiver, and the input selector 73-i in order torecirculate the signal. Photodiodes or some other such devices may beused for each wavelength selected appropriately. Control system 8provides control of elements of the system may be implemented, forexample, as digital logic, software, an FPGA, or a combination of theforegoing. Any other suitable implementations of the control system 8may be used as well.

According to another aspect of the present disclosure, a demultiplexer,SLMs, signal couplers, fiber amplifiers, and the multiplexer may beprovided on vessel 2 to perform two stage amplification. In anotherembodiment, a complete digital system with control logic, receivers andtransmitters may be provided on vessel 2 in order to perform complete 3Rregeneration on both vessels.

Additional variations may include deploying more than two vessels and/orpassing the signal between three or more of vessels, and four or anynumber of vessels may form the recirculating loop; using pointingmethods instead of just one corner cube or reflecting surface; and/or orusing different telescopes for transmission receiving, including usingone or both SLMs as lenses of variable focal length in addition to otherfunctions. Although described as the first vessel and the second vessel,and although described sometimes with reference to satellites, aircraft,hot air balloons, drones, ships, stationary sea structures, such as oilrigs and buoys and the like, the second vessel may in fact be a naturalobject, such as a planet or a moon or an atmosphere of a planet or anaturally occurring medium therein, or may be a surface of an existingmanmade structure, such as an existing satellite or the like. Also,while described as two vessels a vessel may be a node in a terrestrialdata center or the like and the free space, or using a waveguideimplementation may be provided in a data center, such as on or at or inconjunction with a rack-mounted system comprising computers and otherelectrical components.

In another embodiment, storage may be in a rack. In this case, thetransmitting and receiving equipment is placed in a rack, or in anyother machine, media and/or suitable structure, and an optical fiber, orany other suitable transmission medium will be connected to saidtransmitting and receiving equipment, for example an optical waveguide.Amplifiers, a data management system, encryption system and/orcompression system may be included. In a preferred embodiment, a loop ofoptical fiber may be provided with the opposite ends of the opticalfiber connected to each other, for example, via an optical coupler. Inthis case, a laser, maser, or other optical signal, carrying data may betransmitted into the recirculating loop and thereafter make roundtripsthrough the loop such that the data is stored while in motion in theform of a laser beam, maser beam, or other optical signal within theloop.

FIG. 20 illustrates an example of a basic concept of a signal, such asan laser, maser, optical beam or other optical signal (including UV andIR signals), encoded with data via modulation, and travelling through anoptical loop 100. Coupler 101 couples at least a portion of the signalinto the recirculating loop 100, which may be formed by a waveguide,such as an optical fiber, in the looped configuration discussed above.The signal may be recirculated indefinitely in the loop by incorporatinginto the loop such equipment as is needed to balance amplification andloss of the signal contained within, and occasional regeneration tocompensate for other errors, or dispersion, inherent in the opticalfiber or any other optical transmission medium. Part of the signal isthen coupled out of the loop by coupler 101 on each round trip. Coupler101 that provides signal for the optical loop 100 may include a numberof components. For example, an input coupler that provides signal forthe optical loop 100 may be a different component than the outputcoupler that receives signal from the optical loop 100, and suchcomponents may be integrated, or may be positioned adjacent or remotefrom each other, and may be positioned at different parts of the opticalloop 100. The signal may circulate in a counterclockwise direction (asillustrated), or in a clockwise direction, or in both directions as willbe discussed below.

As illustrated in 24B, a spool of optical fiber may be used as awaveguide that connects the transmitting and receiving hardware, suchthat the transmitting and receiving hardware may positioned in the samefacility or remote from each other. A second such optical fiber-basedconfiguration may be positioned in the same facility as the firstconfiguration to provide redundant safety and backup for the data storedin the first configuration. The second such optical fiber-basedconfiguration may store data additional to the first configuration, ormay be linked with the first configuration to form a signalrecirculating loop. The second such optical fiber-based configurationmay be positioned remote from the first configuration or as part of thesame facility. One or both of such configurations may be provided on orat a computer rack or may be provided on their own. Also, one or both ofsuch configurations may be incorporated as integral parts of a unit thatstores data.

FIG. 21 illustrates an exemplary embodiment of an electronic controlsystem to enable management of the data recirculating in a continuousloop-based storage in motion system 99 to store data in a recirculatinglaser, maser or other optical signal in accordance with an embodiment ofthe present disclosure. Various requests for updating the data stored inthe system 99, such as instructions for writing, reading, and erasingdata may be received by control logic 104.

A signal coupler 101 may have inputs A and B and outputs C and D. InputB receives the optical signal and data from the recirculating loop 100while input A receives data from the remaining portion of the system 99.Similarly, output C of signal coupler 101 may be connected to insert theoptical signal and data into the continuous loop 100 while output D maybe provided to multiplexer 118 which separates the signals into a numberof separate channels 119 which are sent to data acquisition component120 to retrieve data from the loop 100. Part of the optical signal,which may be electromagnetic radiation including a laser signal, or thelike, will be coupled from input A of signal coupler 101 to output D ofsignal coupler 101, so that the signal and data may be injected into theloop 100. Similarly a portion of the signal entering input B maycontinue onto output D, recirculating within the loop, while theremaining portion of the circulating signal, may be output throughoutput C of the signal coupler 101 as described above. The couplingratio of this coupler nay be chosen to ensure that the output signal hassufficient strength to allow detection and the recirculation signalcontinues to circulate in the loop without degradation that would leadto data loss.

Signal reamplifier 102 (1R regeneration station) may control the peakintensity of the signal as the signal recirculates through therecirculating loop 100. The signal is maintained within an acceptablepower level by gain, chosen to balance round-trip losses, by the signalreamplifier 102. More than one such signal reamplifier may be requiredto achieve gain stability, prevent undesired nonlinear interactions, orto prevent damage to components resulting from high intensitiesimmediately after the reamplifier. If the signal is comprised of anumber of different light wavelengths, fiber modes, or other separablebeams then separate signal amplifiers 102 may be provided for eachwavelength, wavelength range, mode, or beam in combination with a systemof demultiplexing & multiplexing to guide each beam, wavelength,wavelength range, or mode to the appropriate amplifier.

Also illustrated in FIG. 21 is a loss modulator 103 that destroys aportion of the signal passing through in order to erase the portion ofthe signal corresponding to a particular data block. According to anaspect of the disclosure, a specific portion or pulse of the signalcorresponding to the particular memory block and the data carriedtherein may be erased by modulating the loss of the recirculating loopby the use of a loss modulator (“eraser”) 103, such that the signalpassing through the loop 100 at a given moment, as dictated by delaygenerator 107, may be erased. In this way, a portion of the signal, andthe data carried therein can be eliminated without purging of the signalin its entirety. In the case of a multiplexed signal, a buffer, such as3R buffer 126, may be used to restore signal channels that were erased,together with the target signal channel that was intended to be erased,at the moment that they passed through eraser 103. That is, based ondata provided by 3R buffer 126, all the data erased at the timingprovided by delay generator 107 may be restored, except the signalchannel carrying the data block to be erased. Alternatively, the erasermay comprise a demultiplexer, multiple loss modulators, and amultiplexer configured such that a signal beam may be erased withouterasing all the other beams that share a time slot with that beam, thusavoiding the need for rewriting using the 3R buffer. While the lossmodulator 103 is provided to erase data, any other suitable erasingelement may be used as desired.

Control logic 104 may receive instructions from outside the system 99,such as write, update, read, and/or erase, as well as a clock signal,such as a signal from a computer clock, for example, embodied forexample as a chip, or from another type of clock, such as an atomicclock. Control logic 104 then may look up, using address table 106, atiming of the pulse in the desired recirculating signal, or portion ofthe recirculating signal, corresponding to the data block to be erased,read, or written. In particular, control logic 104 may signal the delaygenerator 107 to generate a timing signal, such as delayed pulses, toeraser 103, or via electrical connection 127 to control output of adesired block of data. Electrical connection 145 outputs the target datato outside the system responsive to the request. Thus, a function of thecontrol logic 104 may be to control the electronics to maintain a table106, such as an address or name table. The information stored thereinmay be given to delay generator 107 to produce appropriately timedsignals to carry out operations such as “write,” that is, to put datainto the recirculating loop 100 for example at the next available slotor at a specific address, depending on the request received. Accordingto an aspect of the disclosure, the write instruction may entail readingall blocks of data that share a timeslot with the target address intothe 3R buffer 126, erasing all blocks of memory sharing the sametimeslot in the loop 100, and writing input bits into the newly emptyslot. Then, using the 3R buffer 126, the data block may be rewrittenbecause channels of the block of data had been erased during the writingprocess, although an alternative implementation of the eraser may avoidthis last step as described above.

This process of timing via addressing relies on the ability of the delaygenerator to track the circulation of the pulse through the loop veryprecisely, in order to reckon when delayed pulses or equivalent timingmethods should be sent to various devices. This may be accomplished bydead reckoning. Another tracking approach is use of a Kalman filter,which combines dead reckoning based on characterization of the systemwith periodic checking of the position of the data in the system. Suchchecking, or resynchronization, may be accomplished by a specificresynchronization block stored in the system, or else by periodicallypolling stored data blocks. Another such operation is the “read”operation, which may, for example, entail reading a specified data blockthat corresponds to an address retrieved from address table 106according to timing of a portion of the signal. Also, all informationstored in the loop 100 may be permanently deleted by shutting off the 1Rregeneration station 102 or by modulation the loop loss, for instance bymeans of the eraser 103, in response to a purge instruction illustratedin FIG. 21 as being received via electrical connection 129.

Address table 106 may also store information to associate the addressingof blocks of data with physical values of the pulses passing through therecirculating loop 100. The signal may be multiplexed and thus thecontrol logic 104 may have to account for more than one channel ofinformation passing through the loop at any given time. For example,address table 106 may be configured as a random access memory or othertype of memory. Delay generator 107 may be a portion of control logic104, but may be a separate component that generates delayed controlsignals to components that interact with loop 100 so as to delayappropriately the control signal to access the correct pulse or portionof the signal passing through the loop 100. Alternatively, thiscomponent could be omitted by using a bit timing scheme that aligns withthe provided clock. In this method all operations could be carried outusing normal clock cycles instead of generating delays.

A fixed delay 109 in the delayed write instruction may be calculated sothat it takes into account the difference in propagation delay throughthe loop path to and through the signal modulator 113.

Signal modulator 113 may receive as input a series of delayed electricpulses via electrical connection 111 from the delay generator 107 andproduces a signal, for instance by modulating a provided optical beamfrom a source not shown in FIG. 21 that carries a signal encoding datain its modulation 115 delayed with the same timing as the pulses in theinput signal 111. For a multiplexed signal, signal modulator 113 maycomprise a series of similar devices, each configured to encode datainto a different channel, or it may be one or more device(s) that isindependently configurable to control which signal channel it producesdepending on the control signal 114.

Input buffer 110 may read and store input bits (new data to be added tothe loop 100) while waiting for them to be encoded and then input intothe loop 100. When triggered by a pulse 108 from the delay generator107, the input buffer 110 may send a signal via electrical connection111 containing the bits to be encoded to the modulator 113 via the inputdemultiplexer 112, with the appropriate delay. Input buffer 110 may be aconventional electronic memory, such as RAM. Such an electric signalcontains the bits to be carried from the input buffer 110 to signalmodulator 113 via the input demultiplexer 112, delayed by an appropriateamount of time to align with the intended block of data in the loop 100.

The input demultiplexer 112 may be provided to control which channel(i.e. wavelength, spatial mode, direction, etc.) the delayed INPUTsignal 111 gets written into by the signal modulator 113, based upon thecontrol signal 114 from the control logic 104. Input demultiplexer 112may be incorporated into the signal modulator 113 in some embodiments ormay be completely absent, in which case the delay generator 107generates different delayed pulse signals 108 for different inputchannels (that is, for different wavelengths, spatial modes, directions,etc.).

Input multiplexer 116 couples signal 115 from one or more differentchannels (i.e. wavelengths, spatial modes, directions, etc.) into onebeam 117 that travels to the signal coupler 101. In the exampleillustrated in FIG. 21 only one signal may be multiplexed at a time, butaccording to an aspect of the present disclosure, many input signals maybe multiplexed simultaneously and/or asynchronously to the signalcoupler 101. Signal coupler 101 then injects a portion of the signalcarrying information encoded in its modulation into the loop 100.According to an aspect of the disclosure, multiple independent channelscarrying signals in different ways, including but not limited todifferent wavelengths, spatial modes, directions, etc., may be injectedinto loop 100 at the same time to increase the amount of data that maybe stored in the loop 100.

Output demultiplexer 118 receives signal output from output C of thesignal coupler 101, and divides each channel, as separated by differentphysical attributes including but not limited to wavelength, spatialmode, and direction, into separate signals.

Data acquisition (DAQ) 120 may receive signal through fiber 119 fromoutput demultiplexer 118 and may demodulate the information encoded inthe modulation of light into digital information encoded in electricalsignals. DAQ 120 may include a physical photodetector, such as aphotodiode, and a sampling analog-to-digital converter (ADC) whosetiming may be determined by a series of delayed pulses 121 generated bythe delay generator 107. Using DAQ 120 one or more specific blocks ofmemory may be read out of the loop 100 in a digital information format.Any suitable device or element may be used to demodulate data asdesired.

DAQ 120 may be provided as a series of different DAQ systems to decodeeach channel of the demultiplexed signals 119, in which case the delayedpulse signal 121 received from delay generator 107 may be received via acorresponding number of different data lines, or may be a signal systemcombining a signal DAQ system with a configurable output demultiplexer118 controlled by a control signal from the control logic 104 or thedelay generator 107. In particular, delayed electric pulses received viaelectrical connection 121 trigger the reading of data in a particularmemory block. These pulses correspond to the points in time when the DAQ120 should sample the signal to capture the desired data. Depending onthe implementation of the DAQ 120, electrode 121 may be a bus connectingto each of the DAQs or a single line (for example, if the channelselection is being performed by the output demultiplexer 119).

In this way, line 122 feeds data, encoded in digital electrical signalsto logic and/or software that performs a cyclic redundancy check (CRC),or equivalent error correcting code or forward error correction method,123, which checks data integrity on the data received in order tocorrect errors.

Asynchronous regeneration management may be provided such that completeregeneration (3R) of the signal may not be performed at the same timefor the entire signal. Instead, according to asynchronous regenerationmanagement, the process may be staggered using delay generator 107 ofcontrol logic 104 illustrated in FIG. 21. This may be necessary, asdiscussed, because 3R regeneration may take longer than the time ittakes for the entire signal to pass through the optical fiber.

For example, an algorithm for asynchronous regeneration may use a signalscheduling thread that schedules regeneration operations based on theavailability of the necessary subcomponents and a separate operationthread that signals the delay generator 107 when scheduled regenerationstasks are to be performed. The scheduling thread may schedule theregeneration of the data block that has been regenerated the leastrecently at the next available opportunity, then proceed to scheduleregeneration for the next least recently regenerated data block, and soon. If all the components are available, for instance, because currentlyno regeneration, write, or erase operation is scheduled, the next suchopportunity could be to perform the reception step the next time thedata block in question passes the coupler 101, followed by erasing thedata block the next time that data block passes the eraser 103 and thenretransmitting the data stored in the 3R buffer 126 to arrive when thenewly empty time slot next passes. This final step may be broken up intomultiple steps aligned for each pass, for instance, because the signalmodulator 113 comprises fewer modulators than the number of multiplexedchannels stored by the system, or because the modulator that writes to aparticular channel is already scheduled for another operation.Therefore, the scheduler would schedule these steps with the operationthread that would signal the delay generator 107 appropriately.

The next data block that the scheduling thread schedules forregeneration (“least recent data block”) may be scheduled to beperformed before the regeneration of the previous data block scheduled,simultaneous with the regeneration of the previous data block, or withthe steps of the regenerations of both data blocks performed interleavedinstead of strictly following the previous data block's successfulregeneration. Thus, regeneration management may be performed in such anasynchronous manner. Other algorithms for scheduling regenerations arealso contemplated. A more dense use of the various resources may beobtained by prioritizing operations that can be performed moreimmediately instead of scheduling operations in the aforementionedsequential scheduling order. One example of such an algorithm might usea nonlinear fitting algorithm, for instance the Levenberg-Marquartmethod, to maximize resource usage to minimize the time required toregenerate all the data blocks. Similarly, other thread structures mightbe used, including parallel scheduling, and single-threaded combinedscheduling and operations. An algorithm for writing data into the systemmay similarly select data blocks to which to write the new data on thebasis of optimizing resource usage or on the basis of minimizingregeneration time.

CRC 123 may perform cyclic redundancy check to ensure data integrityonly for the data block on which 3R is being performed or which is beingread. The system thus has sufficient time to do the integrity check aswell as to generate the portion of the signal corresponding to the datablock. CRC may perform this each time 3R is performed on the data block.While discussed as electrical connections or lines, it will beunderstood that line 122 and other lines may be provided as buses or maybe communicated via radio frequency or other frequency electromagneticradiation, optical signals or the like.

According to an aspect of the disclosure, each data block may be taggedwith a “header” or other forms of tagging that identifies the block andthe header may be encoded with the data block as part of the signal paththrough recirculating loop 100. In this embodiment Address table 106preferably maintains an association between the tag, such as anidentification number written in the header of the data block and a userfor an electronic communication associated with the user. In this way,the data block with the correct header would be read out of therecirculating loop 100 and provided to the output for furtherprocessing. Alternatively the data block could be stored temporarily inan output buffer 47, for instance to coordinate output with the providedclock. Such data management, including an address table 106, may beprovided outside the system and the control logic 104 may receive onlythe header information, so that control logic 104 may return the datablock corresponding to the header requested. For clarification, “header”can mean any other form of tagging.

Switch 125 may control, based on a control signal received viaelectrical connection 126, whether the data 124 is output via output pin145, 146 to outside the data storage system 99, for example, in answerto a request for data received from a user, or fed to the 3R buffer 126via connection 128 for 3R regeneration, based on the control signal 126.Instead of outputting the data directly, the data may be stored in anoutput buffer 47 until requested.

The 3R buffer 126 may hold data while awaiting delayed pulses 127 fromthe delay generator 107 to properly time the process of 3R regeneration(i.e. “Reamplification, Retiming, and Reshaping”). In this embodiment,3R regeneration may be accomplished by receiving the signal, erasing it,and retransmitting it as a new signal. However, alternate 3R methods arecontemplated, such as all-optical regeneration. For every family of datablocks that share a time slot (signal channels that share a time slot),the whole family may be fed into 3R buffer 126. Then the signal for thattime slot may be erased using the erase delayed pulse line 128. Delayedpulses sent via electrical connection 127 may trigger the retransmissionat appropriate times. 3R buffer 126 may also serve a similar purposeduring the WRITE process, by holding the data that must be regeneratedas a result of erasing the time slot to clear a slot for writing if suchan eraser implementation is used. In this case, no erase delayed pulsemay need to be transmitted via 128, but instead reading out of 3R buffer126 follows complete transmission of the input bits. Another variationincludes using an addressing scheme in the 3R buffer 126 such that datain the 3R buffer 126 may be output in any selected order, enablingfaster asynchronous implementation of rewriting multiple data blocks atonce.

As discussed, delayed pulses may be transmitted via electricalconnection 127 from delay generator 107 to trigger transmission of datain the 3R buffer 126, generated in the same way as the delayed pulsestransmitted via line 108 to trigger the writing from the input buffer110. These may be preceded by a delayed pulse on the erase delayed pulseline 108 b in order to erase the appropriate time slot, except in thecase of finishing a WRITE operation, in which case the time slot isalready cleared and pulses will be generated to retransmit the dataimmediately after completing the transmission of the desired input bits.

Delayed pulses, as discussed, may also be transmitted from delaygenerator 107 via electrical connection 108 b to trigger erasing desiredtime slots using the eraser 103 either as part of 3R regeneration, or anERASE operation to erase data securely and permanently. Data may beerased after it is no longer in use, or it will eventually interferewith other signals due to dispersion-induced broadening, although thismay be most easily accomplished by simply not performing 3R regenerationon it the next time its time slot is being regenerated.

PURGE data line 129 may control the power of the 1R regeneration processthrough an inverter. If this line is set to “1”, the 1R regenerationwill shut off, such that amplification of the signal in the loop willstop and the data carried therein will be destroyed rapidly, securely,and irreversibly.

FIG. 22 is an example of a continuous recirculating loop for datastorage, for instance as the loop 100 in FIG. 21, in which a spool ofoptical fiber 13 is used as the waveguide. An unmodulated optical signalmay be provided to signal modulator 113 by light source 1, which may bea fiber laser. Alternately, the light source 1 may be directlymodulated, replacing the signal modulator 113. For instance, if thelight source is a semiconductor cavity laser the signal may be modulatedby modulating the pump current.

1R regeneration station 102 may be a fiber laser amplifier or may bereplaced using a distributed gain system along the length of opticalfiber 12. For example, distributed Raman amplification or opticalparametric amplification may be used. Optical fiber spool 13 may be ananostructure optical fiber waveguide. “Nanostructured optical fibers”may have a radial index profile designed so that the modes are confinedto a relatively small area while using a relatively large outer radiusso that the fiber is not single-moded. Contemplated as nanostructuredoptical fibers are families of technologies including, for example, a“ring fiber” having a first region, a second region, and a third region,where the first region is a cylinder, the second region is a cylinderwith radius greater than the radius of the first region and enclosingthe first region, and the third region is a cylinder with radius greaterthan that of the second region and enclosing both the first and secondregions, such that the second region has an optical refractive indexgreater than both the first and second regions. The first region may beair or fiber. A “vortex fiber” has a first region, a second region, anda third region, and a fourth region, where the first region is acylinder, the second region is a cylinder with radius greater than thatof the first region and enclosing the first region, the third region isa cylinder with radius greater than that of the second region andenclosing both the first and second regions, and the fourth region is acylinder with radius greater than that of the first region and that ofthe second region and enclosing the first, second, and third regions,and where the first region and the third region both have an opticalrefractive index greater than both the second and fourth regions. A“Multicore Fiber” (also called Supermode Fiber or Photonic LanternFiber) has at least two disjoint core regions and a cladding regionwhere the core regions are all cylindrical and the cladding region is acylinder with radius greater than the radius of any of the core regionsand the cladding region encloses all the core regions and where the coreregions each have an optical refractive index greater than the claddingregion. “Optical Wire” having a first region which is a cylinder withrefractive index greater than that of air (where the air acts as thecladding). And “Photonic Crystal Fiber” which is made of a great numberof open cylinders or other open shapes, such as polygons or stars, oftenof varying radii filled with air or lower refractive index glass, oftenwith the center region filled with high-index glass. The optical fiber12 or the spool of optical fiber 13, for example, may be Corning SMF 28or some equivalent thereof, however, PM fiber may also be used, forexample, to increase the extinction ratio of the modulator. The controlsystem 8 may be similar to the system illustrated in FIG. 21. Eraser 103and/or the signal modulator 113 may include Mach-Zehnder (MZ) intensitymodulator(s) 14 and polarization controller(s) 5, as illustrated in FIG.23, with or without an amplifier, controlled by the control system 8 viaelectrical connection 10. Control system 8 may include control logic104, address table 106, delay generator 107 and other such components.

FIG. 23 illustrates an example of signal modulation, for instance as thesignal modulator 113 and/or the eraser 103. First, the polarization(i.e. the waveguide or fiber mode) of the incoming optical signal may becontrolled by a polarization controller 5. In the preferred embodiment,this is accomplished by an inline fiber Polarization Controller. Thiselement may not be necessary if the fiber or waveguide 9 is a PM fiber.Similarly, polarization controller 5 may be unnecessary if the systemwere modified for space-division multiplexing (SDM) or if a modulator 14which does not depend on polarization is used.

Optical intensity modulator 14 may be a Mach-Zehnder (MZ) intensitymodulator that receives an electronic control voltage from RF driver 24via electrical connection 22 which is driven by a signal from thecontrol system 8 via connection 20, which may be an element ofelectrical connection 10 in FIG. 22. This could be replaced by adifferent electro-optical modulator (EOM), an acousto-optic modulator(AOM), or other modulator, such as an electro-absorption modulator(EAM). For other keying schemes, for example, (PSK), a phase modulatormay be used instead.

An optical amplifier may provide gain to control the power of thesignal. Optical isolators 15 and 17 may be used to preventback-reflections that may cause amplifier instability. A second opticalmodulator 18, with associated RF driver 25 and electrical connection 21may provide a greater extinction ratio in the modulated signal than onemodulator alone, for example to provide better differentiation of “1”sand “0”s.

FIG. 25 illustrates an example of the recirculating continuous loop fordata storage in motion using wavelength-division multiplexing (WDM) forsystem 99 a and illustrating a scheme where individual channels may beerased without erasing channels in the same time slot. Wavelengthdivision demultiplexer 31 demultiplexes the signal passed from opticalfiber 12 (or other waveguide). The signal includes n-distinctwavelengths, λ_(n) representing n-distinct fiber channels, each channelcarrying only one wavelength, λ_(i). This may be realized by an arrayedwaveguide grating (AWG) or by n-different fused-fiber couplers that arewavelength-specific and cascaded serially along length of optical fiber12. While shown schematically in FIG. 25 as being positioned as part ofthe recirculating loop 100, it will be understood that the WDM circuit98 a may be positioned outside the recirculating loop such that the WDMcircuit 98 a multiplexed signal may be injected into the recirculatingloop 100 by one or more signal couplers.

Wavelength division multiplexer 32 combines or multiplexes n-distinctfiber channels, each channel for one wavelength, λ_(i), into one fiberor waveguide. The multiplexed signal may thus store information inn-distinct wavelengths λ_(n). This may be implemented, e.g., asn-different fused-fiber couplers 101-1, 101-2, . . . 101-n, that arewavelength-specific and are cascaded serially along the length ofoptical fiber 12, or as an integrated device similar to an AWG, orequivalent technique.

FIG. 25 illustrates elements that describe the n wavelength channelsindexed as element number-channel number. Thus, the 33^(rd) element inthe fourth channel would be referred to as 33-4. 102-i is a 1Rregeneration station for the signal of wavelength λ_(i) in channel i.Some details of this are visible in FIG. 26. According to the exampleprovided in FIG. 25, inter-wavelength equalization may be provided whereeach channel is normalized to a predetermined power, independent of thepower provided to other channels. Such channel-normalized gain may beeither active or passive. A signal control system may provide activeequalization of all the channels using further electrical connections.

Round trip loss modulator 103-i may be a multiplexed implementation oferaser 103 illustrated in FIG. 21 and may be implemented following FIG.23. The round trip loss modulator 103-i erases data of wavelength λ_(i)in channel i of the signal.

Signal coupler 101-i may be a component of signal coupler 101illustrated in FIG. 21 and may inject the signal carrying the dataportion of wavelength λ_(i) into channel i and out of channel i usingtwo inputs a and b into outputs c and d. This may be accomplished usingfused fiber couplers utilizing evanescent coupling of guided waves, forexample, with a coupling wavelength of λ_(i). Light source 1-i mayprovide a modulated or unmodulated optical signal at wavelength λ_(i).

Signal modulation of each channel may be performed by a modulator ofwavelength λ_(b) details are shown in FIG. 23. DAQ 120-i demodulates thesignal in channel i into electrical signals, for instance using aphotodiode. Alternatively, another means of demodulation could be used.

FIG. 26 is a detailed schematic illustration of an example of a 1Rregeneration unit, for instance 102 in FIG. 21 or 22 or 102-i in FIG.25. An optical amplifier 46, for instance a doped fiber amplifier,amplifies the signal in the relevant channel. The gain of this amplifiershould be selected to fully compensate for round-trip losses and mayneed to be provided in multiple separate stages. Optical isolators maybe used to prevent back reflections which may cause amplifierinstability.

Nonlinear intensity filter 48, or an equivalent active and/or passivemeans of control and/or stability may be used. The nonlinear intensityfilter 48 provide higher loss for signals of very low or very highintensity. This provides active and/or passive control of signalintensity to stabilize the 1R regeneration process for uniform,controlled, indefinite maintenance of the peak intensity of signals inthe fiber loop, as illustrated in FIGS. 30 and 31. Alternatively, anexample of an active implementation of the filter 48 may include a99%/1% fused fiber coupler, a power meter connected to the 1% channel ofsaid coupler, and a variable optical attenuator, such as an EAM, drivenby a control system. For instance, a discreteproportional-integral-derivative (PID) controller taking as input thepresent and past power of a given data block may be used to controleither the gain of the amplifier 46, for instance by modulating the pumpcurrent of the amplifier 46, or the loss, for instance using anelectro-absorption modulator (EAM).

FIG. 27 is a schematic illustration of an example of a storage systemutilizing SDM (or Mode Division Multiplexing, MDM) 99 b. A spool ofmultimode optical fiber (MMF) 52 propagates signals in different spatialmodes, such as orbital angular momentum (OAM) carrying modes, in amanner that enables effectively distinguishing between channels withsufficiently low crosstalk to make the system practical. This may berealized by a custom nanostructured fiber designed to minimize bothdistributed and perturbation mode coupling between different modes (i.e.channels). For instance, multimode optical fiber 53 and spool ofmultimode optical fiber 52 may be vortex fiber, multicore fiber(including supermode fiber and photonic lanterns), optical wire,photonic crystal fiber, and/or any other form of fiber or waveguide withthe desired properties. Digital multiple-input multiple-output (MIMO)techniques may be used to digitally demultiplex spatial modes that havemixed by coupling during propagation. Such an approach could entailconversion to a digital signal each round trip. Alternately, themode-selective coupler 54-i may be designed to be wavelength insensitiveand/or may use another coupling method other than fused fiber couplers.The polarization controller 5-i before each coupler 54-i may or may notbe necessary depending on the design of the coupler 54-i and themultimode fiber 53. For instance, if the multimode fiber enablesdistinguishing of modes by preventing intermodal mixing duringpropagation than the polarization controller 5-i would not be necessary.However, if the multimode fiber enables distinguishing of modes by aMIMO technique, the polarization controller 5-i may be necessary, andindeed the polarization controller 5-i may itself be used as a means ofdistinguishing modes in some multimode fibers in place of bothnanostructured fiber and MIMO techniques. Similarly, some designs of thecoupler 54-i may require a polarization controller inserted in thesingle mode fiber 9 before the coupler input a. If multimode opticalfiber 53 or the spool of multimode optical fiber 52 are polarizationmaintaining or nanostructured fibers designed to prevent mode couplingthen they must be of the same type of fiber.

Fused fiber coupler 54-i includes two inputs (a & b) and two outputs (c& d) to couple one specific spatial mode guided by the MMF 53 at aspecific frequency into a single mode optical fiber (SMF) 9 such asCorning SMF28 (or other type of waveguide) with some reasonable couplingratio. Optical intensity modulator 103 may be used to erase targetsignals or portions of signals. A Mach-Zehnder interferometer may beused. Control of this component is performed via the control system 8and the electrical connection 10.

The reamplifier 102 may be substantially similar to the reamplifier usedin other embodiments, as illustrated in FIG. 26. Different componentsmust be chosen, for instance multimode fiber 12 matching the fiber spool53 instead of single mode fiber. Fiber amplifiers 46 based on this samecustom nanostructured MMF 53 doped with a gain medium, for instanceerbium, have been demonstrated and may be used to provide gain to allthe modes simultaneously with low differential mode gain (DMG). However,other amplifiers could be used including, but not limited to, SMF EDFAsin concert with multiplexers and demultiplexers. The nonlinear filter 48(or equivalent active or passive means of control equalization) may belikewise substantially similar, but may require different componentchoices and/or may need to further provide differential mode loss (DML)via either active or passive means to compensate for DMG in theamplifier 46.

FIG. 28 illustrates an example of propagation-direction divisionmultiplexing (DDM)-based storage system 99 c, according to an aspect ofthe disclosure. Higher capacity for the storage in motion system 99 cmay be provided, leveraging the lack of a distinct beginning and endingof the recirculating continuous loop.

In particular, the signal to be injected may be broken up into a firstpart to be propagated clockwise and a second part of the signalpropagating counterclockwise. Thus, the components are duplicated intotwo counter-propagating channels with corresponding indices, that isclockwise channel 1 and counterclockwise channel 2. The DDM may beprovided in addition to one or more additional multiplexing schemes.

As illustrated in FIG. 28, a first coupler 61 injects signal propagatingclockwise into the waveguide loop 12 via connection a of the firstcoupler 61 and removes the signal propagating counterclockwise therefromvia connection b of the coupler 61. A fused fiber coupler usingevanescent coupling of the guided waves may be preferred. Similarly, asecond coupler 62 injects the signal propagating counterclockwise intothe waveguide loop 12 via connector a of the second coupler and removesthe signal propagating clockwise from the waveguide loop 12. Thecouplers 61 and 62 on work in concert to multiplex simultaneously theDDM signals and to collectively serve as the lone signal coupler 101 ofFIG. 21.

Further, couplers 63, having an input C, an output B, and abidirectional connection A, may be provided to separate input and outputcomponents. Optical isolators 64 may be provided to prevent signalchannel crosstalk.

To build one embodiment, the techniques of WDM, SDM, and DDM illustratedin FIGS. 25, 27, and 28 may be combined into one system using all threeschemes, as well as other possible schemes, simultaneously. To do this,the signal coupler 101-i in each wavelength channel illustrated in FIG.25 may be replaced, according to an aspect of the disclosure, with anarray of fused fiber couplers, as illustrated, for example, in FIG. 27,including replacing each component 1-i through 11-i with an array ofsuch components for each mode. In addition, additional multiplexingschemas may be added using the direction division multiplexing (DDM)technique together with other modulation methods to allow additionalstorage by providing multiples bits in each signal. For example,quadrature modulation (QAM) or quadrature phase-shift keying (QPSK). Ina free-space embodiment, a combination of polarization multiplexing andSDM may be necessary to achieve capacity equivalent to SDM fiber modemultiplexing since spatial modes in free space lack inherentpolarization like waveguide modes, such as optical fiber modes, have.

FIG. 30 illustrates an example of a nonlinear filter that providesstability in a passive way in order to control round trip gain of thesignal in the loop and reduce noise that may otherwise accumulate in theloop. Noise reduction may be accomplished by a saturable absorber 140.Low-finesse etalon 141 made of a material with a high optical Kerreffect (for example, SbSI, Zn, Se, or GaAs) may be used to provide gainstabilization. The etalon may be tuned such that at low intensities ithas 100% transmissivity, that is, the wavelength or set of wavelengthsare resonant wavelengths of the material. However, as the intensity ofthe pulse rises, the refractive index of the material may change thuschanging the transmissivity of the etalon. The reflected power may thenbe absorbed by optical isolator 14.

FIGS. 31A-F illustrates an example of how a nonlinear filter,illustrated by way of example in FIG. 30, provides stability for roundtrip gain control and how it may be tuned. In FIG. 31A, signal gain isillustrated for a typical laser amplifier. FIG. 31B illustrates thevarious passive elements in the system, including the signal coupler orsignal couplers, end facets, and modulators that provide linear loss.FIG. 31C illustrates that a saturable absorber provides loss in the sameway that the signal amplifier provides gain, however for practicalreasons as discussed below, the saturable absorber may be chosen with ahigher loss than the signal amplifier's gain and with a much lowersaturation point.

FIG. 31D illustrates a nonlinear etalon that provides reflectivityaccording to the formula

$R = {1 - \frac{1}{1 + {{\mathcal{F}sin}^{2}( {2\pi \; {klI}} )}}}$

where F is the etalon finesse, k is the wavenumber of the light, l isthe length of the etalon cavity, and I is the intensity of the signal.

FIG. 31E illustrates that without the filter, all noise is amplified andstability may be achieved only in the amplifier saturation region. Anattempt to control gain at a lower level by tuning γ_(a)−l_(b)=0 may beinherently unstable because even if slightly positive it may lead intothe amplifier saturation region, and if it is even slightly negative,the signal pulse may die to zero.

FIG. 31F illustrates the stability control and noise reduction with anonlinear filter added. With the filter added, first, low-level noisethat is less than the saturation of the saturable absorber, I_(c),suffers round trip losses. Second, a stable point may be reached at apoint in intensity before the amplifier saturation region, and this maybe adjusted by adjusting this filter. Accordingly, the filter may betuned in the following way:

Noise-cutting may be tuned to remove noise more efficiently by raisingthe saturable absorber loss, which should exceed γ_(a)−l_(b). However,it may be tuned down to reduce systematic round trip losses that maylimit system performance, or may be tuned up if noise is being generatedfaster than it is dying out.

The point of stability may be tuned by adjusting the etalon finesse orthe Kerr constant of the etalon.

If multiple equally-spaced wavelengths are in use, the length of theetalon may be tuned so that each wavelength is a resonant wavelength ofthe etalon.

In this way, a stable, wavelength-insensitive amplification (at specificdiscrete wavelengths) may be achieved in a tunable fashion well belowthe saturation region of the laser amplifier, or at the same time,signal noise may be reduced.

Similar filtering may be done for phase shift keying, or similarphase-sensitive keying schemes such as QAM, using phase-sensitivefilters or phase-sensitive amplification. According to one embodiment,optical parametric amplification (OPA) with a phase-matched pump andidler may be used to provide amplification selectively to signals thatfulfill the phase matching condition set by the signal and idler whileproviding loss to signals that are shifted from the phase matchingcondition by greater than π/2 radians. In this configuration, one pumpmay serve for multiple signals, although effects of intermodaldifferences in effective refractive index may be considered to ensurethat each signal has a properly phase matched idler. Also, for signalsof different wavelengths, an idler at the correct wavelength and phasefor each signal must be provided which may correspond to the usualrelationship ω_(s)+ω_(i)=2ω_(p). Similarly, schemes with multiple pumpsmay be used to provide different wavelength and/or phase matchingconditions. Alternatively, two pumps of different wavelengths with therelationship ω_(p1)+ω_(p2)=2ω_(s) may be used. In such a case, no idlermay be needed because in effect each signal serves as its own idler. Inorder to keep the pump and idler phase matching relationship constant,the pump and idler may need to be periodically rephrased and/orreplaced. This may be accomplished, for instance, by removing them fromthe loop each round trip using a wavelength filter which blocks theidler(s) and pump(s) but not the signal(s) so that the pump(s) andidler(s) may be constantly provided by, for example, a constant wave(CW) laser source. Therefore, such an idler would provide amplificationto signals of any phase instead of providing phase-selectiveamplification as desired. Similarly, the idler could have sufficientpower to avoid depletion (after considering the gain that it experiencesfrom the amplification of the signal). Other phase-sensitive orphase-selective elements may provide the same or similar functionality,such as an injection-locked fiber amplifier.

In another embodiment, the recirculating loop may comprise an opticalcavity which stores the data. FIG. 32A illustrates an example where thiscavity may be formed by two or more receiver-transmitter pairs“Reflector A” and “Reflector B” which may each act as a reflector tokeep the data stored in beams of light 156 between them. Using similarcomponents to the systems described above, an optical signal may begenerated by the light sources 1A and 1B, which may then be modulated bysignal modulators 113A and 113B and transmitted to the signal receiver120B or 120A, which may demodulate the signal and convert it intoelectrical data. The control systems 8A and 8B may selectively controlthe receiving and retransmitting of the data, so there may be no needfor the eraser 103. Similarly, the signal may be fully regenerated eachtime it is received and retransmitted, so there may be no need for thesignal conditioner 102. Coupling data out as an electrical signal and/orperforming data operations, such as read, write, or erase, may beperformed at either or both Reflectors using similar methods to thosedescribed above. Similarly, error correction may be applied at bothreflectors, one reflector, or intermittently. Multiplexing may be addedusing an array of receivers and transmitters or by adding additionalmultiplexing and demultiplexing elements as illustrated in FIG. 29.

Alternatively, turnaround of the signal may be accomplished by mirrors,as illustrated in FIG. 32B. In this embodiment, the signal beam 156 maybe travelling in both directions and in other embodiment may travel inmultiple directions or in one direction. the signal beam 156 may bestored in a reflective cavity using two mirrors 152 to keep the beam inthe cavity. The mirrors 152 may be designed to keep the beam in thecavity in a stable manner, many methods of which are well known. Similarto the fiber embodiment, an eraser 103 to erase signals and a signalconditioner 102 comprising a gain medium 153 and a nonlinear filter 48may be provided inside the cavity. The nonlinear filter 48 may be activeor passive, as described above, and may provide round trip stability ofgain and loss and/or noise reduction.

The input signal 158 may be coupled into the system and the outputsignal 159 may be coupled out of the system using, for instance, a beamsplitter 160, which may perform the same function as the coupler 101 inFIGS. 21, 22, 25, and 27. Alternately, one or more of the mirrors 152may be partially transmissive so that an appropriate fraction of thesignal 156 stored in the cavity is coupled out through saidpartially-transmissive mirror each round trip. Signal generation andsignal detection may be accomplished in a manner similar to FIG. 22,using a laser source 1 and a signal modulator 113 to write data into thesystem and a signal demodulator 120 to demodulate the output signal 159.An optical isolator 64 may be provided to prevent back-reflected beamsfrom entering the signal generator 1.

Many other cavity designs and sizes are contemplated. For example, acavity may include many flat mirrors and/or lenses with a parabolicmirror at each end, which may provide steering stability to the beam. Inanother example, the cavity may be formed using one or more non-flatreflective surfaces which reflect the signal beam 156 several times eachround trip. An example is illustrated in FIG. 32C, where the cavity maybe one ellipsoidal curved reflective surface 162. In this embodiment,the input/output coupler may be a partially transmissive portion 161 ofthe reflective surface 162 which allows an input beam 163 into thecavity and couples an appropriate fraction of the power in the cavityout each round trip as the output beam 164, similar to coupler 101 inFIG. 21. The input beam 163 and output beam 164 may be generated andreceived using the same method described above. To provide erasing andsignal conditioning, elements may be inserted within the cavity in thepath of the signal beam, for instance an eraser 103 and a gain medium153. A nonlinear filter 48 or multiplexing elements may be provided, asdescribed above.

The present system, method, and devices, may be implemented usingcomponents implemented as hardware, software, firmware or a combinationof the foregoing, and may be implemented in one or more computer systemsor other processing systems, such that no human operation may benecessary. A computer or computer systems that implement the componentsof Earth station 20 a,b, and that implement the controllers of thesatellites, of the transceivers on Earth station 20 a,b, and on thesatellites, of the electromagnetic signal generators and regenerators,and the like, may each include or be provided as one or more processorsin one or more units for performing the method according to the presentdisclosure. One or more or all of these computers or processors may beaccessed via the internet or other communication networks and/or means.Two or more of these units, or components of these units, may beexecuted on, or be performed by, processes running on a single device oron a series of such devices, for example as one or more rack-mounteddevices. The communication interface with Earth station 20 a,b hereindescribed may include wired or wireless interface communication, and maycommunicate via a wire, cable, fire optics, a telephone line, a cellularlink, satellite connection a radio frequency link, such as WI-FI, orother such communication channels and networks including wireless orwired communication, or via a combination of the foregoing.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. Also,components or other structures or systems, features or steps, describedwith respect to one implementation, for example, a satellite or vesselfree space implementation, a rack free space implementation, or awaveguide implementation, may also be deployed or used with respect toanother implementation. Components noted as being part of the samestructure may be packaged as separate components or structures, andcomponents described as packaged separately may be integrated orprovided together. Also, components may be provided remote from thestructures with which they are logically associated or with which theydirectly communicate.

Steps outlined in sequence need not necessarily be performed insequence, not all steps need necessarily be executed and otherintervening steps may be inserted. Therefore, that the present inventionbe limited not by the specific disclosure herein.

What is claimed is:
 1. A data storage system comprising: a recirculatingloop configured to maintain a laser signal carrying the digital data inmotion and including an optical waveguide, an optical waveguide coupler,and a regenerator; a signal generator configured to generate a lasersignal carrying the digital data and to transmit the laser signal intoan input/output optical waveguide; the optical waveguide couplercoupling the laser signal between the input/output optical waveguide andthe optical waveguide; and the regenerator coupled to the opticalwaveguide and configured to at least one of amplify and regenerate thelaser signal through the optical waveguide.
 2. The system of claim 1, adata management system configured to manage digital data in the datastorage system, wherein the recirculating loop comprises an eraserconfigured to erase, according to timing based on information providedby the data management system, a portion of the laser signal carrying ablock of data of the digital data, the portion of the laser signal beingless than an entirety of the laser signal.
 3. The system of claim 1,wherein the signal generator is configured to generate a multiplexedsignal as the laser signal, the multiplexed signal comprising a firstset of multiplexed laser signals, such that a first multiplexed lasersignal of the first set carries data other than a second multiplexedlaser signal of the first set, each laser signal of the first set ofmultiplexed signals comprising a second set of multiplexed laser signalsgenerated using a multiplexing scheme different from the multiplexingscheme used to generate the first set of multiplexed signals.
 4. Thesystem of claim 3, wherein each laser signal of the second set ofmultiplexed laser signals comprises a third set of multiplexed lasersignals generated using a multiplexing scheme different from themultiplexing scheme used to generate the first set of multiplexedsignals and from the multiplexing scheme used to generate the second setof multiplexed signals.
 5. A data storage system comprising: arecirculating loop configured to maintain a signal carrying data inmotion and including a waveguide and a waveguide coupler; the waveguidecoupler configured to couple a signal carrying the data into thewaveguide; and a signal conditioner configured to condition the signalconveyed through the waveguide by at least one of amplifying andregenerating the signal.
 6. The system of claim 5, wherein the waveguidecomprises optical fiber.
 7. The system of claim 5, further comprising asignal generator configured to transmit the signal to the waveguidecoupler, wherein the signal generated by the signal generator is anelectromagnetic signal.
 8. The system of claim 5, further comprising alaser signal generator configured to transmit a laser signal as thesignal to the waveguide coupler.
 9. The system of claim 5, wherein therecirculating loop comprises the signal conditioner, and the signalconditioner comprises a signal amplifier configured to amplify at leasta portion of the signal each time the signal passes through the signalconditioner.
 10. The system of claim 5, further comprising: a datamanagement system configured to manage data in the data storage systemand configured to receive a request from outside the data storage systemto at least one of delete, write and update a block of data in the data,wherein the recirculating loop comprises an eraser configured to erase,based on information received from the data management system, a firstportion of the signal, the first portion carrying the data block, thedata block being less than an entirely of the data.
 11. The system ofclaim 10, wherein the data management system is configured to generatetiming information according to the request, and the informationreceived by the eraser from the data management system is the timinginformation.
 12. The system of claim 5, further comprising a signalgenerator configured to transmit the signal to the waveguide coupler,wherein the signal carrying the data generated by the signal generatoris a signal multiplexed by a propagation-direction multiplexerconfigured to transmit a first portion of the signal through therecirculating loop in a first direction and to transmit a second portionof the signal through the recirculating loop in a second directiondifferent from the first direction.
 13. The system of claim 5, thesystem comprising a signal regenerator, wherein the signal conditioneris a signal amplifier configured to amplify at least some of the signal,wherein, the signal regenerator is configured to regenerate, at a firsttiming, only a first portion of the signal, the first portion of thesignal being less than an entirety of the signal, and to regenerate, ata second timing after the first timing, only a second portion of thesignal, the second portion of the signal being less than an entirety ofthe signal.
 14. The system of claim 13, wherein the system regeneratesthe signal asynchronously such that prior to the first timing, thesecond portion was regenerated less recently than the first portion. 15.The system of claim 13, wherein the system regenerates only the firstportion of the signal at a third timing, and regenerates only the secondportion of the signal at a fourth timing, an interval between the firstand third timing being different from an interval between the second andfourth timing.
 16. The system of claim 5, further comprising: acontroller configured to receive, at a first time, a first request fromoutside the data storage system to perform a first operation, the firstoperation comprising one of a read operation, a write operation, and adelete operation for a first block of data of the data, and to receive,at a second time after the first time, a second request from outside thedata storage system to perform a second operation, the second operationcomprising one of the read operation, the write operation, and thedelete operation for a second block of data of the data, wherein thesystem performs the first operation after performing the secondoperation.
 17. The system of claim 16, wherein when the first operationis the read operation, the second operation is the read operation; whenthe first operation is the write operation, the second operation is thewrite operation, and when the first operation is the delete operation,the second operation is the delete operation.
 18. The system of claim 5,the system comprising a data integrity determiner configured todetermine data integrity only of the first portion when the signalregenerator regenerates the first portion, and to determine dataintegrity only of the second portion when the signal regeneratorregenerates the second portion.
 19. The system of claim 5, wherein thesystem further comprises an error checker configured to ensure dataintegrity.
 20. The system of claim 5, wherein the recirculating loopfurther comprises a signal filter configured to impose signal loss onthe signal in dependence, in a non-linear manner, on signal intensity ofthe signal.
 21. The system of claim 5, wherein the recirculating loopfurther comprises a signal filter configured to filter out noise withintensity below a first value.
 22. The system of claim 5, wherein therecirculating loop further comprises a signal filter configured toprovide signal loss to a first portion of the signal, the first portionof the signal having a signal intensity greater than a second portion ofthe signal.
 23. The system of claim 5, wherein the recirculating loopfurther comprises a signal filter configured to provide signal loss to afirst portion of the signal and to a second portion of the signal, thefirst portion having a signal intensity greater than the second portion,wherein the signal loss provided to the first portion is greater than aroundtrip gain, and the signal loss provided to the second portion isless than the roundtrip gain.
 24. The system of claim 5, wherein therecirculating loop further comprises a signal filter comprising amaterial with a first index of refraction, the signal filter configuredto provide a signal loss to a first portion of the signal with a signalintensity below a first value, and to change the index of refraction ofthe material so as to provide a signal loss to a second portion of thesignal with a second intensity higher than the first value.
 25. Thesystem of claim 5, wherein the waveguide coupler comprises a firstcoupler and a second coupler, the first coupler configured to coupleonly a first portion of the signal, and the second coupler configured tocouple only a second portion of the signal other than the first portion,wherein the first and second portions are multiplexed in the signal aspart of a first multiplexing scheme.
 26. The system of claim 24, whereinthe first coupler comprises a third coupler and a fourth coupler, thethird coupler configured to couple only a third portion of the signalother than the second portion, and the fourth coupler configured tocouple only a fourth portion of the signal other than the second portionand other than the third portion, wherein the first portion comprisesthe third and fourth portions, and the third and fourth portions aremultiplexed in the signal as part of a second multiplexing schemedifferent from the first multiplexing scheme.
 27. The system of claim 5,wherein the waveguide coupler comprises a signal in-coupler configuredto transmit the signal into the waveguide, and a signal out-couplerconfigured to remove signal from the waveguide, wherein the signalin-coupler is positioned at the recirculating loop remote from thesignal out-coupler.
 28. The system of claim 5, further comprising: asignal generator configured to transmit the signal to the waveguidecoupler, wherein the signal generator is configured to generate amultiplexed electromagnetic signal as the signal, the multiplexedelectromagnetic signal comprising a first set of multiplexedelectromagnetic signals, such that a first multiplexed signal of thefirst set carries data other than a second multiplexed signal of thefirst set, wherein each signal of the first set of multiplexedelectromagnetic signals comprises a second set of multiplexedelectromagnetic signals generated using a multiplexing scheme differentfrom the multiplexing scheme used to generate the first set ofmultiplexed electromagnetic signals.
 29. The system of claim 28, whereineach laser signal of the second set of multiplexed electromagneticsignals comprises a third set of multiplexed electromagnetic signalsgenerated using a multiplexing scheme different from the multiplexingscheme used to generate the first set of multiplexed electromagneticsignals and from the multiplexing scheme used to generate the second setof multiplexed electromagnetic signals.
 30. The system of claim 5,further comprising: a signal generator configured to transmit the signalto the waveguide coupler, wherein the signal generator is configured togenerate a code division multiplexed signal as the signal, the codedivision multiplexed signal comprising a first set of multiplexedsignals such that a first multiplexed signal of the first set carriesdata other than a second multiplexed signal of the first set.
 31. Thesystem of claim 5, further comprising: a signal generator configured totransmit the signal to the waveguide coupler, wherein the signalgenerator is configured to generate an orbital angular momentum divisionmultiplexed signal as the signal, the orbital angular momentum divisionmultiplexed signal comprising a first set of multiplexed signals suchthat a first multiplexed signal of the first set carries data other thana second multiplexed signal of the first set.
 32. The system of claim 5,further comprising: a signal generator configured to transmit the signalto the waveguide coupler, wherein the signal generator is configured togenerate a space division multiplexed signal as the signal, the spacedivision multiplexed signal comprising a first set of multiplexedsignals such that a first multiplexed signal of the first set carriesdata other than a second multiplexed signal of the first set.
 33. Thesystem of claim 5, further comprising: a signal generator configured totransmit the signal to the waveguide coupler, wherein the signalgenerator is configured to generate a polarization division multiplexedsignal as the signal, the polarization division multiplexed signalcomprising a first set of multiplexed signals such that a firstmultiplexed signal of the first set carries data other than a secondmultiplexed signal of the first set.
 34. The system of claim 5, furthercomprising: a signal generator configured to transmit the signal to thewaveguide coupler, wherein the signal generator is configured togenerate a wavelength division multiplexed signal as the signal, thewavelength division multiplexed signal comprising a first set ofmultiplexed signals such that a first multiplexed signal of the firstset carries data other than a second multiplexed signal of the firstset.
 35. The system of claim 5, further comprising: a data managementsystem configured to associate a data block carried by a portion of thesignal with at least one of a physical property and a location of theportion of the signal; and a controller configured to generate a controlsignal controlling an operation on the data block, the control signalgenerated based on a clock signal with reference to the at least one ofthe physical property and the location of the portion of the signal. 36.The system of claim 5, further comprising: a data management systemconfigured to manage data in the data storage system and configured toreceive a request from outside the data storage system to at least oneof delete, write and update a block of data in the data, wherein therecirculating loop comprises an eraser configured to erase, based oninformation received from the data management system, a first portion ofthe signal, the first portion carrying the data block, the data blockbeing less than an entirely of the data.
 37. The system of claim 5,wherein the signal conditioner is configured to provide a first signalgain to a first portion of the signal, wherein the first signal gain isprovided according to information regarding signal intensity obtainedfor a previous round trip of the signal through the recirculating loop.38. The system of claim 5, wherein the signal conditioner is configuredto provide filtering of the signal by providing signal amplification toa first portion of the signal, wherein the signal amplification isprovided to the first portion when the first portion meets aphase-matching condition.
 39. The system of claim 38, wherein the signalconditioner is configured to provide a pump beam and an idler beam, thepump beam and the idler beam configured to provide the filtering.
 40. Adata storage in motion system comprising: a recirculating loopcomprising an optical cavity configured to maintain an optical signalcarrying data in motion, and the recirculating loop including a signalcoupler, a first signal returner, and a signal conditioner configured tocondition the signal by amplifying the signal; the signal couplerconfigured to couple at least a portion of the signal into the opticalcavity by transmitting the signal to the first signal returner; thefirst signal returner positioned and configured to return the signal tothe signal coupler; the signal coupler configured to return the signalreceived from the first signal returner to the first signal returner;and a signal regenerator configured to regenerate, at a first timing,only a first portion of the signal, the first portion of the signalbeing less than an entirety of the signal, and to regenerate, at asecond timing after the first timing, only a second portion of thesignal, the second portion of the signal being less than an entirety ofthe signal.
 41. The system of claim 40, wherein the system regeneratesthe signal asynchronously such that prior to the first timing, thesecond portion was regenerated less recently than the first portion. 42.The system of claim 40, wherein the signal coupler comprises a signalin-coupler configured to transmit the signal into the optical cavity,and a signal out-coupler configured to remove signal from the opticalcavity, wherein the signal in-coupler is positioned at the opticalcavity remote from the signal out-coupler.
 43. The system of claim 40,wherein the loop comprises a second signal returner, and the firstsignal returner is configured to return the signal to the signal couplerby transmitting the signal to the second signal returner.
 44. The systemof claim 40, wherein the first signal returner returns the signal byreflecting the signal off a reflecting surface.
 45. A data storagemethod using a recirculating loop configured to maintain a signalcarrying data in motion and including a signal introducer and a signalreturner, the method comprising; introducing, by the signal introducer,the signal carrying the data into the recirculating loop; returning, bythe signal returner, the signal to the signal introducer; and returning,by the signal introducer, the signal received from the signal returnerto the signal returner.
 46. The data storage method of claim 45, whereinthe signal returner is a waveguide, and the signal introducer is awaveguide coupler configured to couple the signal between a signalgenerator and the waveguide.
 47. The data storage method of claim 45,wherein the signal returner comprises a reflecting surface.
 48. The datastorage method of claim 47, wherein the signal introducer is positionedon a vessel.
 49. The data storage method of claim 45, furthercomprising: recirculating a first portion of the signal through therecirculating loop in a first direction; and recirculating a secondportion of the signal through the recirculating loop in a seconddirection different from the first direction, the second portion beingother than the first portion.
 50. The method of claim 45, wherein asignal generator is configured to generate a multiplexed electromagneticsignal as the signal, the multiplexed electromagnetic signal comprisinga first set of multiplexed electromagnetic signals, such that a firstmultiplexed signal of the first set carries data other than a secondmultiplexed signal of the first set, wherein each signal of the firstset of multiplexed electromagnetic signals comprises a second set ofmultiplexed electromagnetic signals generated using a multiplexingscheme different from the multiplexing scheme used to generate the firstset of multiplexed electromagnetic signals.
 51. The method of claim 45,wherein each signal of the second set of multiplexed electromagneticsignals comprises a third set of multiplexed electromagnetic signalsgenerated using a multiplexing scheme different from the multiplexingscheme used to generate the first set of multiplexed electromagneticsignals and from the multiplexing scheme used to generate the second setof multiplexed electromagnetic signals.
 52. The method of claim 45,wherein a signal generator is configured to generate a code divisionmultiplexed signal as the signal, the code division multiplexed signalcomprising a first set of multiplexed signals such that a firstmultiplexed signal of the first set carries data other than a secondmultiplexed signal of the first set.
 53. The method of claim 45, whereina signal generator is configured to generate an orbital angular momentumdivision multiplexed signal as the signal, the orbital angular momentumdivision multiplexed signal comprising a first set of multiplexedsignals such that a first multiplexed signal of the first set carriesdata other than a second multiplexed signal of the first set.
 54. Themethod of claim 45, wherein a signal generator is configured to generatea space division multiplexed signal as the signal, the space divisionmultiplexed signal comprising a first set of multiplexed signals suchthat a first multiplexed signal of the first set carries data other thana second multiplexed signal of the first set.
 55. The method of claim45, wherein a signal generator is configured to generate a polarizationdivision multiplexed signal as the signal, the polarization divisionmultiplexed signal comprising a first set of multiplexed signals suchthat a first multiplexed signal of the first set carries data other thana second multiplexed signal of the first set.
 56. The method of claim45, wherein a signal generator is configured to generate a wavelengthdivision multiplexed signal as the signal, the wavelength divisionmultiplexed signal comprising a first set of multiplexed signals suchthat a first multiplexed signal of the first set carries data other thana second multiplexed signal of the first set.
 57. The method of claim45, wherein a data management system is configured to associate a datablock carried by a portion of the signal with at least one of a physicalproperty and a location of the portion of the signal; and the methodfurther comprising: generating a control signal controlling an operationon the data block, the control signal generated based on a clock signalwith reference to the at least one of the physical property and thelocation of the portion of the signal.
 58. The method of claim 45,wherein a data management system is configured to manage data in thedata storage system, and the method further comprises: receiving arequest from outside the data storage system to at least one of delete,write and update a block of data in the data; and erasing, by an erasercomprised in the recirculating loop, based on information received fromthe data management system, a first portion of the signal, the firstportion carrying the data block, the data block being less than anentirely of the data.
 59. The method of claim 45, further comprising:providing, by a signal conditioner positioned in the recirculating loop,a first signal gain to a first portion of the signal, wherein the firstsignal gain is provided according to information regarding signalintensity obtained for a previous roundtrip of the signal through therecirculating loop.
 60. The method of claim 45, further comprising:providing, by a signal conditioner, filtering of the signal by providingsignal amplification to a first portion of the signal, when the firstportion meets a phase-matching condition.
 61. The method of claim 45,wherein the signal introducer is a signal coupler connected to a lasertransmitter configured to generate a laser signal as the signal.
 62. Themethod of claim 45, wherein the method further comprises: regenerating,by a signal regenerator, at a first timing, only a first portion of thesignal, the first portion of the signal being less than an entirety ofthe signal, and regenerating, by the signal regenerator, at a secondtiming after the first timing, only a second portion of the signal, thesecond portion of the signal being less than an entirety of the signal,wherein the system regenerates the signal asynchronously such that priorto the first timing, the second portion was regenerated less recentlythan the first portion.
 63. A data storage system comprising: arecirculating loop operable to store signals carrying data in motion,the recirculating loop including a waveguide and including a waveguidecoupler operable to couple the signals carrying the data into thewaveguide; and a signal conditioner operable to amplify or regeneratethe signals, wherein the waveguide coupler is operable to couple a firstsubset of the signals into the waveguide such that the first subset ofsignals travels in the recirculating loop in a first direction, and tocouple a second subset of the signals into the waveguide such that thesecond subset of signals travels in the recirculating loop in a seconddirection opposite the first direction.
 64. The data storage system ofclaim 63, wherein the waveguide comprises an optical fiber, and whereinthe waveguide coupler is operable to couple the first subset of thesignals into the optical fiber such that the first subset of signalstravels through the optical fiber in the first direction, and to couplethe second subset of the signals into the optical fiber such that thesecond subset of signals travels through the optical fiber in the seconddirection opposite the first direction.
 65. The data storage system ofclaim 64, wherein the waveguide coupler comprises a first coupler and asecond coupler, wherein the first coupler is configured to: inject thefirst subset of the signals into the waveguide such that the firstsubset of signals travels in the recirculating loop in the firstdirection, and remove the second subset of the signals from thewaveguide, and wherein the second coupler is configured to: inject thesecond subset of the signals into the waveguide such that the secondsubset of signals travels in the recirculating loop in the seconddirection, and remove the first subset of the signals from thewaveguide.
 66. A data storage system comprising: a recirculating loopoperable to store signals carrying data in motion, the recirculatingloop including a waveguide and a waveguide coupler operable to couplethe signals carrying the data into the waveguide; and a signalconditioner operable to amplify or regenerate the signals, and a signalgenerator operable to provide the signals to the recirculating loop suchthat the signals concurrently traverse the recirculating looprepeatedly, wherein the waveguide coupler is configured to place a firstsubset of the signals into the recirculating loop using a first type ofmultiplexing, and wherein the waveguide coupler is configured to place asecond different subset of the signals into the recirculating loop usinga second type of multiplexing different from the first type ofmultiplexing.
 67. The data storage system of claim 66, wherein thewaveguide coupler is configured to place the first subset of the signalsinto the recirculating loop according to a first channel, the firstchannel corresponding to at least one of a first wavelength, a firstspatial mode, or a first direction of propagation, and wherein thewaveguide coupler is configured to place the second subset of thesignals into the recirculating loop according to a second channel, thesecond channel corresponding to at least one of a second wavelengthdifferent from the first wavelength, a second spatial mode differentfrom the first spatial mode, or a second direction of propagationdifferent from the first direction.
 68. A data storage systemcomprising: a recirculating loop operable to store signals carrying datain motion, the recirculating loop including a waveguide, a waveguidecoupler operable to couple the signals carrying the data into thewaveguide, and a signal amplifier operable to amplify a particular oneof the signals after each cycle of the particular signal traversing therecirculating loop; and a signal regenerator operable to regenerate theparticular signal at a frequency different from a frequency at which theparticular signal is amplified within the recirculating loop.
 69. Thedata storage system of claim 68, wherein the signal amplifier isoperable to control a peak intensity of the particular one of thesignals after each cycle of the particular signal traversing therecirculating loop.
 70. The data storage system of claim 69, wherein thesignal regenerator is operable to regenerate the particular signal byreceiving the particular signal, erasing the particular signal from therecirculating loop, and transmitting a copy of the particular signalwithin the recirculating loop.
 71. A data storage system comprising: arecirculating loop operable to store signals carrying data in motion,the recirculating loop including a multi-mode fiber and an opticalcoupler operable to couple the signals carrying the data into themulti-mode fiber, wherein the optical coupler is operable to couple someof the signals into a first mode of the multi-mode fiber and to coupleother ones of the signals into a second, different mode of themulti-mode fiber.
 72. The data storage system of claim 71, furthercomprising a signal generator operable to generate first and secondorbital angular momentum division multiplexed signals as the signalscarrying data, wherein the optical coupler is operable to couple thefirst orbital angular momentum division multiplexed signals into a firstmode of the multi-mode fiber and to couple the second orbital angularmomentum division multiplexed signals into a second, different mode ofthe multi-mode fiber.
 73. The data storage system of claim 71, furthercomprising a signal generator operable to generate first and secondspace division multiplexed signals as the signals carrying data, whereinthe optical coupler is operable to couple the first space divisionmultiplexed signals into a first mode of the multi-mode fiber and tocouple the second space division multiplexed signals into a second,different mode of the multi-mode fiber.
 74. The data storage system ofclaim 71, wherein the multi-mode fiber is a vortex fiber, a multicorefiber, an optical wire, or a photonic crystal fiber.
 75. A data storagesystem comprising: a recirculating loop operable to store signalscarrying data in motion, the recirculating loop including a waveguide, awaveguide coupler operable to couple the signals into the waveguide suchthat the signals recirculate in the recirculating loop, and a signalamplifier operable to amplify a particular one of the signals after eachcycle of the particular signal traversing the recirculating loop; asignal regenerator operable to regenerate the particular signal at afirst scheduled time; a data acquisition module operable to read theparticular signal from the recirculating loop at a second scheduledtime; and a control module operable to control operation of the signalregenerator and the data acquisition module according to scheduling dataspecifying the first and second scheduled times, wherein the controlmodule is operable to determine each of the first and second scheduledtimes independently of one another.
 76. The data storage system of claim75, wherein the control module is operable to determine the firstscheduled time based on an availability of the signal regenerator toregenerate the particular signal at the first scheduled time.
 77. Thedata storage system of claim 75, wherein the control module is operableto determine the second scheduled time based on an estimated time atwhich the particular signal will pass the waveguide coupler along therecirculating loop.
 78. The data storage system of claim 75, wherein thecontrol module is operable to determine the second scheduled time basedon a read instruction signal identifying the particular signal.
 79. Thedata storage system of claim 78, wherein the control module is furtheroperable to determine a timing of the particular signal using an addresstable.